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

Annotations already declare readOnly, idempotent and openWorld, so the bar is low, yet the description adds substantive behavior: data comes from the board's index rather than the employer's live site, a closed posting means the feed stopped listing it, and the `basis` field must be consulted before asserting a posting is open. That is exactly the caveat an agent needs to avoid misreporting.

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 core question and the return shape, then the caveat. The colon-chained clauses ('with no key, 200 with one') make it slightly dense, but no sentence is 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?

Output schema exists, so return values needn't be explained, yet the description still names `open`, the closed-ids list and `basis`, which is the one output field that changes how results should be interpreted. Nothing an agent needs to call or report on this tool is 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% and the schema already documents the maxItems cap and notChecked overflow, so the description starts from a strong baseline. It still adds real value with the 50-without-a-key vs 200-with-a-key distinction and the id provenance ('Job ids from search_jobs'), which the schema does not spell out.

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 opening question 'Are these postings still on the board?' plus the return shape 'open:{id:boolean} and the closed ids' define a specific verb and resource: batch liveness verification of job postings. This clearly separates it from detail-fetching siblings like get_job and get_jobs.

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?

're-verify a saved shortlist before acting on it' names the situation the tool is for, and 'read `basis` before telling a person a posting is open' names a precondition for downstream use. The 50-vs-200 cap with/without a key gives concrete invocation guidance that no sibling provides.

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