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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuine context beyond that: it enumerates the metrics returned and explains the fallback behavior when no company is supplied, which the annotations cannot convey. Pagination and response shape are unaddressed, keeping it off a 5.

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?

Two sentences, front-loaded with the scope statement and then the enumeration of metrics, with the no-argument fallback called out last. It is dense but every clause carries information; the 'What Haystack knows about' framing is slightly wordy but sets context efficiently.

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?

Because there is no output schema, the description must describe returns — and it does, listing each metric by name. With only one optional string parameter and full annotation coverage, nothing critical is missing; only paging/multi-employer behavior is left implicit.

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% and the sole parameter is fully documented with an example and a leave-out instruction, so the baseline is 3. The description restates the omit-for-top-employers behavior but adds no format, casing or matching semantics (e.g. partial names) 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 names a concrete resource (employer-level hiring facts) and enumerates the specific payload: live roles, reply share, median time to first reply, form field count and questions. It is clearly distinct from get_job/search_jobs, though it never explicitly contrasts itself with application_system_facts, which sounds adjacent.

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 one concrete usage rule — omit the company argument to get employers most likely to reply — which is real guidance. But there is no explicit statement of when to choose this over application_system_facts or search_jobs, so the agent has to infer the boundary between them.

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