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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds real behavioral context beyond that: the caller_verifies status and the meaning of 'when true, open the cited text before relying on it', plus the warning that a citation is provenance, not truth or currency. That interpretive layer is exactly what annotations cannot express.

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?

Front-loaded with the purpose, then input, then output, then the follow-up routing and the caveat — a sensible order with no filler. The closing caveat is dense but each clause carries distinct meaning, so it earns its space.

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?

There is no output schema, and the description compensates by naming the returned fields (answer, results with id/title/url, caller_verifies) and explaining the one non-obvious field's contract. Combined with the explicit follow-up routing, an agent has everything needed to call and interpret this 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%, so q and limit are fully documented in the schema and the description only restates them ('Input: q (query) and limit'). No added syntax, format, or interaction detail for the parameters; baseline 3 is appropriate when the schema does the work.

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?

States a specific verb and resource ('Search Pauhu's sourced index') plus the return shape ('cited results as JSON'). The final sentence explicitly routes to the sibling source_fetch_fragment, so an agent can distinguish it from the other source_* tools without opening a schema.

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?

Gives a clear trigger for the follow-up tool ('For one result's citation link, call source_fetch_fragment with the same q and limit and the result id'), which is unusually actionable. It does not distinguish this from siblings like pauhu_search or source_verify_bearing, so it stops short of the full when-not coverage a 5 requires.

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