pin_history

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Beyond the readOnlyHint annotation, the description discloses ordering behavior (newest first), the audit content (who changed it and when), and the projection semantics of the `fields` parameter (full record by default, 'headers' for the usual listing set, enumerated field names). It also explains the size rationale and recommends fetching individual records afterward, adding meaningful behavioral context.

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?

The description is dense but well-structured: purpose and ordering come first, then parameter behavior, then usage rationale. Every sentence carries distinct information, and the longer middle sentence is justified by the need to enumerate valid field values and explain the 'headers' shortcut.

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?

For a read-only tool with two parameters, an output schema, and no nested objects, the description covers purpose, ordering, projection semantics, and size-driven usage guidance. An agent has enough information to decide when to call it and how to set `fields`; return-value details are appropriately left to the output schema.

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?

The `fields` parameter is thoroughly described: allowed values are enumerated, the special 'headers' value is defined, and the default behavior when omitted is stated. The `key` parameter is only implicitly explained as the pinned entry's key, but that is sufficiently clear given the tool name and required schema.

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?

The description states a specific purpose: returning the full version history of a pinned entry by key, newest first, framed as an audit of who changed it and when. This clearly distinguishes it from siblings like pin_get or pin_list by focusing on the historical record rather than current state or a simple list.

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?

The description gives explicit guidance for the `fields` parameter: use it when a long history listing would otherwise be too large, since bodies dominate the response size, and fetch wanted bodies individually afterward. It does not explicitly contrast against sibling tools like pin_get or pin_list, but the usage context for the optional projection is clear.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.