callers_of

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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior. The description adds valuable context beyond this: it returns only direct callers, provides exact file:line call sites, and is based on the resolved call graph rather than guesses. This is genuine disclosure of behavioral traits.

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?

Three sentences, each earning its place: what it returns, how it behaves, and when to choose siblings instead. The core value is front-loaded and there is no filler.

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 single-parameter tool with a fully described schema and strong annotations, the description is complete. It covers the return content, the granularity (direct callers, exact call sites), and the key alternative tools, leaving no important gap for an agent deciding or invoking the tool.

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% and thoroughly documents the query parameter, including short and fully qualified names and the ambiguous-name refusal behavior. The description's 'one level up' phrasing slightly reinforces the query's meaning, but it does not add material semantic value 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 states a specific verb and resource: returns direct callers with exact call sites (file:line) from the resolved call graph. It also differentiates this tool from siblings like impact_of and references_of, making its scope clear.

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 explicitly frames when to use this tool: to answer 'who uses this?' one level up. It even gives alternatives for adjacent cases: use impact_of for full blast radius and references_of for dynamic-dispatch hits, which is strong routing guidance.

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