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

Annotations already declare destructiveHint, idempotentHint, and non-readOnly, but the description adds genuinely non-structured context: no email is sent, the thread stops reading as pending, and the action is reversible via done:false. It does not cover failure modes (e.g., marking an already-closed deal) or permission requirements.

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 dense sentences with no filler, and the core effect (records placement as done) is front-loaded. The mid-sentence clause about telling the other party via send_reply is slightly convoluted but still carries necessary information.

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 2-parameter mutation tool with no output schema, the description covers the side effects, the notification gap, and reversibility. Remaining gaps (error behavior when already closed, any auth constraints) are minor given the annotation coverage.

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 description coverage is 100% and both parameters are already documented, including the done true/false semantics. The description only restates the reopen behavior for done:false, adding no syntax, defaults, or constraints beyond the schema; the baseline of 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 concrete verb+effect: it records that a placement is done (link live or deal agreed) and closes the agreed placement on the thread. It distinguishes itself from send_reply by explicitly saying it sends no email, so an agent can tell the two apart without opening the 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?

It gives a clear usage condition (the link is live or the deal is agreed) and an explicit routing rule: use send_reply first because this tool does not notify the other party. It also documents done:false for reopening. It stops short of contrasting with the similarly-scoped sibling archive_thread.

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