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

Annotations already declare destructive=true, readOnly=false, and idempotent=false, so the danger profile is covered structurally. The description adds genuine value beyond that by stating the key becomes permanently unusable and that the machine may or may not have been created. It does not say what happens if the stop already executed or what error surfaces for an invalid/used key.

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?

Only two sentences, so size is good, but the first sentence is convoluted and front-loads an ambiguous clause ('before locating/stopping a possibly created computer') rather than the primary action. The second sentence is crisp and earns its place.

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?

This is a destructive, non-idempotent mutation with a single undocumented parameter and no output schema, yet the description omits what the call returns, what happens when the underlying stop has already completed, and what states produce errors. For a destructive cancellation tool, that leaves meaningful gaps an agent must guess at.

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 0% for the single 'key' parameter, so the description must carry the meaning — and it does partially, clarifying that the key is a request key tied to a pending stop request. It adds no detail on key format, provenance (presumably from machine_request), or validation behavior.

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 specific action (cancelling the request key) and hints at why (a computer may already have been located/stopped), but the phrasing 'before locating/stopping a possibly created computer' blurs whether the tool stops a machine, cancels a pending stop request, or both. An agent cannot confidently distinguish its effect from siblings like machine_stop or key_revoke based on this text alone.

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?

No when-to-use guidance is given and no alternative is named, even though machine_stop, key_revoke, and machine_request_stop plausibly overlap. The only usage-adjacent signal is the implied constraint that a cancelled key cannot be reused, which tells the agent about consequences but not about selection.

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