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

Beyond the annotations (destructiveHint=true, idempotentHint=true), the description discloses the state machine: which statuses are reachable, which are terminal, and that resolvedAt is stamped. This is exactly the mutation semantics an agent needs and cannot get from the annotations alone.

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?

Dense and front-loaded, with the core action first and transition rules after; every sentence carries state-machine information. It is slightly over-packed, and the closing sentence about CLOSED/INVESTIGATING introduces states that complicate rather than clarify.

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?

For a mutation tool with no output schema, the description covers reachable states, terminal states, and side effects well. It is marred by referencing CLOSED and INVESTIGATING destinations that the status enum does not permit, which could mislead an agent about valid inputs.

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?

With 67% schema coverage, the description usefully expands the status enum ('RESOLVED (fixed), WONT_FIX (closed without fix), DEFERRED (parked)') and notes the mutation's effect on resolvedAt. The resolution text parameter's role is only described in the schema, not here.

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 specific verb+resource ('Close out an Issue') and immediately enumerates the three resolution outcomes, distinguishing it from sibling tools like update_issue. An agent knows exactly what operation this performs from the first sentence.

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 explicit eligibility and transition rules ('An OPEN issue reaches RESOLVED, WONT_FIX or DEFERRED directly', 'CLOSED and WONT_FIX are terminal'), which functions as strong when-to-use/when-not guidance. It never names the obvious alternative (update_issue) for non-resolution edits, so it stops short of a 5.

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