pin.compare

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

Annotations already establish the tool as read-only, idempotent, and non-destructive. The description adds meaningful behavioral context: it produces 'changed paths' as output and is 'bounded' in scope, which clarifies the nature of the operation beyond the annotations. No contradiction with annotations.

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 two concise sentences: the first states the core action and the second adds a qualifier and exclusion. Every word earns its place, with no filler or redundancy.

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 simple diff tool, the description, combined with annotations and schema, provides sufficient context for an agent to select and invoke it. It explains the output at a high level (changed paths) and distinguishes from semantic search. The absence of an explicit output format is not critical given the tool's simplicity, but a bit more detail on the return value would improve completeness.

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 description explains that the tool compares 'two hex revisions,' which covers the format and intent of the base and head parameters. However, the repository parameter is not mentioned at all, and with 0% schema description coverage, the description does not fully compensate. The property names are self-explanatory, but the description could be more explicit about all three parameters.

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 verb and resource: 'Diff changed paths between two hex revisions.' It clearly distinguishes the tool from siblings like pin.search_docs and pin.search_code by explicitly noting it is 'not semantic search.' This makes the tool's purpose unmistakable.

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 provides clear context ('Bounded change evidence for reviews') and an explicit exclusion ('not semantic search'), which helps the agent understand when to use this tool versus semantic search tools. However, it does not explicitly name alternative sibling tools or provide a direct when-to-use/when-not-to-use contrast, leaving a minor gap.

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