Mark a tool call as completed by recording its successful finish. Computes duration from the start event and logs an optional summary for telemetry.
v2.1.0 — Record successful completion. Computes durationMs from observe_tool_start. No-op on unknown callId.
| Name | Required | Description | Default |
|---|---|---|---|
| callId | Yes | ||
| result | No | Optional summary string for telemetry. |
Changes observed during successful MCP inspections.
v12.7.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Without annotations, description covers key behavior (no-op on unknown callId, duration computation) but omits side effects or state changes.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Single sentence with version, purpose, and edge case; extremely concise and efficient.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Sufficient for a simple completion logger; covers main action and no-op edge case, though could mention prerequisite observe_tool_start call.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Description adds no meaning for parameters beyond schema; schema already covers callId and result, but callId lacks description.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
Description clearly states it records successful completion and computes duration from observe_tool_start, distinguishing it from sibling error/partial/cancel tools.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
No explicit guidance on when to use this tool versus alternatives like observe_tool_error or observe_tool_partial; usage is implied but not clarified.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.