チュートリアル: ツール使用エージェントの構築

#!/bin/bash
# Ring 1: Single tool, single turn.
# Source for <CodeSource> in build-a-tool-using-agent.mdx.

# Define one tool as a JSON fragment. The input_schema is a JSON Schema
# object describing the arguments Claude should pass when it calls this
# tool. This schema includes nested objects (recurrence), arrays
# (attendees), and optional fields, which is closer to real-world tools
# than a flat string argument.
TOOLS='[
  {
    "name": "create_calendar_event",
    "description": "Create a calendar event with attendees and optional recurrence.",
    "input_schema": {
      "type": "object",
      "properties": {
        "title": {"type": "string"},
        "start": {"type": "string", "format": "date-time"},
        "end": {"type": "string", "format": "date-time"},
        "attendees": {
          "type": "array",
          "items": {"type": "string", "format": "email"}
        },
        "recurrence": {
          "type": "object",
          "properties": {
            "frequency": {"enum": ["daily", "weekly", "monthly"]},
            "count": {"type": "integer", "minimum": 1}
          }
        }
      },
      "required": ["title", "start", "end"]
    }
  }
]'

USER_MSG="Schedule a 30-minute sync with [email protected] and [email protected] next Monday at 10am."

# Send the user's request along with the tool definition. Claude decides
# whether to call the tool based on the request and the tool description.
RESPONSE=$(curl -s https://api.anthropic.com/v1/messages \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "content-type: application/json" \
  -d "$(jq -n \
    --argjson tools "$TOOLS" \
    --arg msg "$USER_MSG" \
    '{
      model: "claude-opus-4-6",
      max_tokens: 1024,
      tools: $tools,
      tool_choice: {type: "auto", disable_parallel_tool_use: true},
      messages: [{role: "user", content: $msg}]
    }')")

# When Claude calls a tool, the response has stop_reason "tool_use"
# and the content array contains a tool_use block alongside any text.
echo "stop_reason: $(echo "$RESPONSE" | jq -r '.stop_reason')"

# Find the tool_use block. A response may contain text blocks before the
# tool_use block, so filter by type rather than assuming position.
TOOL_USE=$(echo "$RESPONSE" | jq '.content[] | select(.type == "tool_use")')
TOOL_USE_ID=$(echo "$TOOL_USE" | jq -r '.id')
echo "Tool: $(echo "$TOOL_USE" | jq -r '.name')"
echo "Input: $(echo "$TOOL_USE" | jq -c '.input')"

# Execute the tool. In a real system this would call your calendar API.
# Here the result is hardcoded to keep the example self-contained.
RESULT='{"event_id": "evt_123", "status": "created"}'

# Send the result back. The tool_result block goes in a user message and
# its tool_use_id must match the id from the tool_use block above. The
# assistant's previous response is included so Claude has the full history.
ASSISTANT_CONTENT=$(echo "$RESPONSE" | jq '.content')
FOLLOWUP=$(curl -s https://api.anthropic.com/v1/messages \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "content-type: application/json" \
  -d "$(jq -n \
    --argjson tools "$TOOLS" \
    --arg msg "$USER_MSG" \
    --argjson assistant "$ASSISTANT_CONTENT" \
    --arg tool_use_id "$TOOL_USE_ID" \
    --arg result "$RESULT" \
    '{
      model: "claude-opus-4-6",
      max_tokens: 1024,
      tools: $tools,
      tool_choice: {type: "auto", disable_parallel_tool_use: true},
      messages: [
        {role: "user", content: $msg},
        {role: "assistant", content: $assistant},
        {role: "user", content: [
          {type: "tool_result", tool_use_id: $tool_use_id, content: $result}
        ]}
      ]
    }')")

# With the tool result in hand, Claude produces a final natural-language
# answer and stop_reason becomes "end_turn".
echo "stop_reason: $(echo "$FOLLOWUP" | jq -r '.stop_reason')"
echo "$FOLLOWUP" | jq -r '.content[] | select(.type == "text") | .text'

#!/bin/bash
# Ring 2: The agentic loop.
# Source for <CodeSource> in build-a-tool-using-agent.mdx.

TOOLS='[
  {
    "name": "create_calendar_event",
    "description": "Create a calendar event with attendees and optional recurrence.",
    "input_schema": {
      "type": "object",
      "properties": {
        "title": {"type": "string"},
        "start": {"type": "string", "format": "date-time"},
        "end": {"type": "string", "format": "date-time"},
        "attendees": {"type": "array", "items": {"type": "string", "format": "email"}},
        "recurrence": {
          "type": "object",
          "properties": {
            "frequency": {"enum": ["daily", "weekly", "monthly"]},
            "count": {"type": "integer", "minimum": 1}
          }
        }
      },
      "required": ["title", "start", "end"]
    }
  }
]'

run_tool() {
  local name="$1"
  local input="$2"
  if [ "$name" = "create_calendar_event" ]; then
    local title=$(echo "$input" | jq -r '.title')
    jq -n --arg title "$title" '{event_id: "evt_123", status: "created", title: $title}'
  else
    echo "{\"error\": \"Unknown tool: $name\"}"
  fi
}

# Keep the full conversation history in a JSON array so each turn sees prior context.
MESSAGES='[{"role": "user", "content": "Schedule a weekly team standup every Monday at 9am for the next 4 weeks. Invite the whole team: [email protected], [email protected], [email protected]."}]'

call_api() {
  curl -s https://api.anthropic.com/v1/messages \
    -H "x-api-key: $ANTHROPIC_API_KEY" \
    -H "anthropic-version: 2023-06-01" \
    -H "content-type: application/json" \
    -d "$(jq -n --argjson tools "$TOOLS" --argjson messages "$MESSAGES" \
      '{model: "claude-opus-4-6", max_tokens: 1024, tools: $tools, tool_choice: {type: "auto", disable_parallel_tool_use: true}, messages: $messages}')"
}

RESPONSE=$(call_api)

# Loop until Claude stops asking for tools. Each iteration runs the requested
# tool, appends the result to history, and asks Claude to continue.
while [ "$(echo "$RESPONSE" | jq -r '.stop_reason')" = "tool_use" ]; do
  TOOL_USE=$(echo "$RESPONSE" | jq '.content[] | select(.type == "tool_use")')
  TOOL_NAME=$(echo "$TOOL_USE" | jq -r '.name')
  TOOL_INPUT=$(echo "$TOOL_USE" | jq -c '.input')
  TOOL_USE_ID=$(echo "$TOOL_USE" | jq -r '.id')
  RESULT=$(run_tool "$TOOL_NAME" "$TOOL_INPUT")

  ASSISTANT_CONTENT=$(echo "$RESPONSE" | jq '.content')
  MESSAGES=$(echo "$MESSAGES" | jq \
    --argjson assistant "$ASSISTANT_CONTENT" \
    --arg tool_use_id "$TOOL_USE_ID" \
    --arg result "$RESULT" \
    '. + [
      {role: "assistant", content: $assistant},
      {role: "user", content: [{type: "tool_result", tool_use_id: $tool_use_id, content: $result}]}
    ]')

  RESPONSE=$(call_api)
done

echo "$RESPONSE" | jq -r '.content[] | select(.type == "text") | .text'

#!/bin/bash
# Ring 3: Multiple tools, parallel calls.
# Source for <CodeSource> in build-a-tool-using-agent.mdx.

TOOLS='[
  {
    "name": "create_calendar_event",
    "description": "Create a calendar event with attendees and optional recurrence.",
    "input_schema": {
      "type": "object",
      "properties": {
        "title": {"type": "string"},
        "start": {"type": "string", "format": "date-time"},
        "end": {"type": "string", "format": "date-time"},
        "attendees": {"type": "array", "items": {"type": "string", "format": "email"}},
        "recurrence": {
          "type": "object",
          "properties": {
            "frequency": {"enum": ["daily", "weekly", "monthly"]},
            "count": {"type": "integer", "minimum": 1}
          }
        }
      },
      "required": ["title", "start", "end"]
    }
  },
  {
    "name": "list_calendar_events",
    "description": "List all calendar events on a given date.",
    "input_schema": {
      "type": "object",
      "properties": {"date": {"type": "string", "format": "date"}},
      "required": ["date"]
    }
  }
]'

run_tool() {
  case "$1" in
    create_calendar_event)
      jq -n --arg title "$(echo "$2" | jq -r '.title')" '{event_id: "evt_123", status: "created", title: $title}' ;;
    list_calendar_events)
      echo '{"events": [{"title": "Existing meeting", "start": "14:00", "end": "15:00"}]}' ;;
    *)
      echo "{\"error\": \"Unknown tool: $1\"}" ;;
  esac
}

MESSAGES='[{"role": "user", "content": "Check what I have next Monday, then schedule a planning session that avoids any conflicts."}]'

call_api() {
  curl -s https://api.anthropic.com/v1/messages \
    -H "x-api-key: $ANTHROPIC_API_KEY" \
    -H "anthropic-version: 2023-06-01" \
    -H "content-type: application/json" \
    -d "$(jq -n --argjson tools "$TOOLS" --argjson messages "$MESSAGES" \
      '{model: "claude-opus-4-6", max_tokens: 1024, tools: $tools, messages: $messages}')"
}

RESPONSE=$(call_api)

while [ "$(echo "$RESPONSE" | jq -r '.stop_reason')" = "tool_use" ]; do
  # A single response can contain multiple tool_use blocks. Process all of
  # them and return all results together in one user message.
  TOOL_RESULTS='[]'
  while read -r block; do
    NAME=$(echo "$block" | jq -r '.name')
    INPUT=$(echo "$block" | jq -c '.input')
    ID=$(echo "$block" | jq -r '.id')
    RESULT=$(run_tool "$NAME" "$INPUT")
    TOOL_RESULTS=$(echo "$TOOL_RESULTS" | jq --arg id "$ID" --arg result "$RESULT" \
      '. + [{type: "tool_result", tool_use_id: $id, content: $result}]')
  done < <(echo "$RESPONSE" | jq -c '.content[] | select(.type == "tool_use")')

  MESSAGES=$(echo "$MESSAGES" | jq \
    --argjson assistant "$(echo "$RESPONSE" | jq '.content')" \
    --argjson results "$TOOL_RESULTS" \
    '. + [{role: "assistant", content: $assistant}, {role: "user", content: $results}]')

  RESPONSE=$(call_api)
done

echo "$RESPONSE" | jq -r '.content[] | select(.type == "text") | .text'

#!/bin/bash
# Ring 4: Error handling.
# Source for <CodeSource> in build-a-tool-using-agent.mdx.

TOOLS='[
  {
    "name": "create_calendar_event",
    "description": "Create a calendar event with attendees and optional recurrence.",
    "input_schema": {
      "type": "object",
      "properties": {
        "title": {"type": "string"},
        "start": {"type": "string", "format": "date-time"},
        "end": {"type": "string", "format": "date-time"},
        "attendees": {"type": "array", "items": {"type": "string", "format": "email"}},
        "recurrence": {
          "type": "object",
          "properties": {
            "frequency": {"enum": ["daily", "weekly", "monthly"]},
            "count": {"type": "integer", "minimum": 1}
          }
        }
      },
      "required": ["title", "start", "end"]
    }
  },
  {
    "name": "list_calendar_events",
    "description": "List all calendar events on a given date.",
    "input_schema": {
      "type": "object",
      "properties": {"date": {"type": "string", "format": "date"}},
      "required": ["date"]
    }
  }
]'

run_tool() {
  case "$1" in
    create_calendar_event)
      local count=$(echo "$2" | jq '.attendees | length // 0')
      if [ "$count" -gt 10 ]; then
        echo "ERROR: Too many attendees (max 10)"
        return 1
      fi
      jq -n --arg title "$(echo "$2" | jq -r '.title')" '{event_id: "evt_123", status: "created", title: $title}' ;;
    list_calendar_events)
      echo '{"events": [{"title": "Existing meeting", "start": "14:00", "end": "15:00"}]}' ;;
    *)
      echo "ERROR: Unknown tool: $1"
      return 1 ;;
  esac
}

EMAILS=$(seq 0 14 | sed 's/.*/user&@example.com/' | paste -sd, -)
MESSAGES="[{\"role\": \"user\", \"content\": \"Schedule an all-hands with everyone: $EMAILS\"}]"

call_api() {
  curl -s https://api.anthropic.com/v1/messages \
    -H "x-api-key: $ANTHROPIC_API_KEY" \
    -H "anthropic-version: 2023-06-01" \
    -H "content-type: application/json" \
    -d "$(jq -n --argjson tools "$TOOLS" --argjson messages "$MESSAGES" \
      '{model: "claude-opus-4-6", max_tokens: 1024, tools: $tools, messages: $messages}')"
}

RESPONSE=$(call_api)

while [ "$(echo "$RESPONSE" | jq -r '.stop_reason')" = "tool_use" ]; do
  TOOL_RESULTS='[]'
  while read -r block; do
    NAME=$(echo "$block" | jq -r '.name')
    INPUT=$(echo "$block" | jq -c '.input')
    ID=$(echo "$block" | jq -r '.id')
    if OUTPUT=$(run_tool "$NAME" "$INPUT"); then
      TOOL_RESULTS=$(echo "$TOOL_RESULTS" | jq --arg id "$ID" --arg result "$OUTPUT" \
        '. + [{type: "tool_result", tool_use_id: $id, content: $result}]')
    else
      # Signal failure so Claude can retry or ask for clarification.
      TOOL_RESULTS=$(echo "$TOOL_RESULTS" | jq --arg id "$ID" --arg result "$OUTPUT" \
        '. + [{type: "tool_result", tool_use_id: $id, content: $result, is_error: true}]')
    fi
  done < <(echo "$RESPONSE" | jq -c '.content[] | select(.type == "tool_use")')

  MESSAGES=$(echo "$MESSAGES" | jq \
    --argjson assistant "$(echo "$RESPONSE" | jq '.content')" \
    --argjson results "$TOOL_RESULTS" \
    '. + [{role: "assistant", content: $assistant}, {role: "user", content: $results}]')

  RESPONSE=$(call_api)
done

echo "$RESPONSE" | jq -r '.content[] | select(.type == "text") | .text'

#!/bin/bash
# Ring 5: The Tool Runner SDK abstraction.
# Source for <CodeSource> in build-a-tool-using-agent.mdx.

# The Tool Runner SDK abstraction is available in the Python, TypeScript,
# and Ruby SDKs. There is no equivalent for raw curl requests. Switch to
# the Python or TypeScript tab to see Ring 5, or keep the Ring 4 loop as
# your shell implementation.