Release a retained closure handle

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

Annotations already declare destructiveHint=true and idempotentHint=false, but the description adds value beyond them: invalidating the returned Reference, the confirm=true requirement, explicit-mutation-approval, and idempotency=contextual-write. It describes what state is mutated, though it doesn't detail failure modes or rate limits.

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?

The critical warning ('WRITES LIVE GAME STATE') and the core action are front-loaded, and the labeled segments (Phase, Requires, Capabilities, Produces, Verify, Safety, On failure) are scannable. It is dense but each clause carries distinct information, with only mild redundancy between the signature block and the schema.

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 safety, prerequisites, verification, and failure handling ('inspect tool-schema for exact fields'). It is largely complete, though 'Produces: structured-result' is vague without an output schema to define the actual return.

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 both key and confirm are fully documented in the schema. The description only restates the signature ('{ key: string, confirm: boolean?, threadContext: number? }') without adding semantic meaning, 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?

The description states a precise verb and resource: 'Remove one key from getgenv().__mcp_closure_refs so cloned/wrapped closures can be garbage-collected.' This is a specific action distinguishable from siblings like list-closure-references or closure-capabilities, and it explains the downstream effect (enabling GC).

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 clear preconditions (requires confirm=true, active-client, explicit-mutation-approval), a phase (act), and a verification path ('Verify with: assert-state'). It does not name a specific alternative sibling or explicitly state when NOT to use it, so it falls just 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.