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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), and the description adds real operational context beyond them: the Pro-plan requirement, fixed 20-per-page pagination, the result ordering (most editions attended, then most recent), the too_broad refusal for oversized editions, and the default of an event's latest 5 past editions.

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 Pro-plan requirement and the core set logic, and every clause (defaults, caps, ordering, returns) carries information. It is dense and relies heavily on parentheticals and dashes, which slightly hurts scannability but not correctness.

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?

With no output schema, the description still enumerates the returned fields (company, hits, last edition and url, total_about, editions_used with as_of) and covers plan gating, pagination, defaults, limits, and failure modes. Nothing an agent needs to call this correctly appears missing.

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 100%, so the baseline is 3, but the description adds meaning the schema does not: that `country` is HQ-based, that `event` without `years` defaults to its latest 5 past editions, and that each side is capped at 5 editions with oversized ones refused. It stops short of documenting the cursor reuse constraint or the role enum values beyond what the schema already states.

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 ('Prospect lists: companies at any `include` edition and at none of the `exclude` editions'), and the set-difference semantics ('at A or B, not at C') separate it cleanly from siblings like search_companies or list_edition_exhibitors without opening either 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 clear context for when this tool applies (cross-edition attendance prospecting) and states the gating prerequisite ('Requires a Pro plan'), plus the too_broad refusal condition. It never explicitly names an alternative tool or a when-not-to-use case, so routing still requires inference.

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