Explain an issue code

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

Annotations already declare readOnly, idempotent, closed-world and non-destructive, so the safety bar is covered. The description still adds genuinely new behavior: it makes no network requests and, more usefully, defines the failure mode ('an unknown code is an error naming the three closest codes'), which tells the agent how to recover from a typo'd or stale code.

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?

Three short sentences, front-loaded with the purpose, then the side-effect profile, then the error contract. No filler and nothing buried.

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?

An output schema exists so return shape needs no explanation, and the description still names the three returned facts. With a single required parameter fully documented and the error path disclosed, an agent has everything needed to call this 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 100% and the schema itself documents the format example (NOINDEX_DETECTED) and the case/`-`-for-`_` forgiveness rule. The description adds nothing beyond that — it only restates that the input is a single issue code — so the baseline 3 applies.

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 ('Says what one vercel-seo-audit issue code means') and enumerates the payload: meaning, reporting module, and category. This is plainly distinguishable from list_checks (enumerate checks) and audit_site (run an audit) without opening any 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?

Usage is implied by 'one ... issue code' — the agent infers it should call this when holding a code from a finding — but there is no explicit when-to-use framing, no prerequisites, and no named alternative for the case where the agent has no code or wants the full list.

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