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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile is covered. The description adds genuinely new traits: the cost model (no scan allowance consumed), the missing-data semantics ('Missing or failed evidence remains unavailable, not zero'), and a trust boundary on quoted source text. These are valuable and non-obvious.

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?

Four short sentences, front-loaded with the defining statement and then the operational caveats. Dense but each sentence carries distinct information; the clipped phrasing is efficient rather than padded.

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?

Behavior is well covered for a read-only, cache-backed tool and annotations carry the safety profile, so no output schema is strictly needed. The notable gap is that the one required parameter is left undefined in both schema and description, which an agent needs in order to call it 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 coverage is 0% and the single required parameter 'source' has no description, type hints, or format. The prose mentions 'source-profile' and 'cited-source' but never explains what value 'source' should take (domain, ID, name) or its maxLength constraint, leaving the required parameter ambiguous.

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 the resource clearly ('saved cited-source profile') and the 'saved' qualifier plus 'reads saved measurements or existing caches' implicitly conveys the retrieval verb. It does not explicitly distinguish itself from near-neighbours like get_citation_sources or get_cited_queries, so an agent must infer the boundary.

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 usefully states that no provider/browser call or scan allowance is consumed, which implies this is the zero-cost path and that a rescan tool (e.g., request_rescan) is the alternative for fresh data. However, that alternative is never named and no explicit when-to-use vs when-not guidance is given.

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