where_used

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds meaningful behavioral detail beyond annotations: resolution is by bare name only, results can mix unrelated same-name symbols, and the reply includes file:line sites, the indexed commit, and whether the checkout has moved on.

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 compact yet information-dense, with the core purpose front-loaded in the first clause. Every sentence earns its place: purpose, blast-radius framing, alternative tool, read-only note, resolution caveat, and return-value summary.

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 tool with no output schema, the description clearly states what the reply contains: every definition and use site as file:line, the indexed commit, and checkout drift status. Combined with annotations covering the read-only and idempotent behavior, an agent has everything needed to invoke this tool correctly.

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?

Schema description coverage is 100%, so both parameters are already documented in the input schema. The description reinforces that name is a bare symbol name and mentions definitions/use sites, but it does not add substantive new meaning beyond the 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 opens with a specific verb and resource: 'answers who defines and who uses one symbol name,' and frames it as the question to ask before changing a function, struct, or variable. It also distinguishes itself from outline by naming the alternative explicitly.

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?

It gives clear when-to-use context ('before changing a function, struct or variable') and names an alternative tool ('Use outline instead to see everything one file declares'). It also warns about the bare-name resolution caveat and tells the agent to open files rather than treat the list as a conclusion.

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