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

Annotations already declare destructiveHint=true, idempotentHint=true and readOnlyHint=false, so the safety profile is covered. The description adds a genuine behavioral constraint not in the annotations: the current session's key is protected from revocation. It does not say whether revocation is immediate or what downstream tokens stop working, which keeps it below a 5.

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?

Two short sentences, zero filler, and the action is front-loaded ahead of the caveat. Every clause 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?

For a one-parameter destructive tool whose annotations already flag destructiveness and idempotency, the description supplies the key missing piece (session-key protection). Residual gaps around immediacy of revocation and any cascading effect on existing sessions are minor.

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?

There is a single parameter with 100% schema description coverage ('Key id (uuid) from the list call'), so the schema already carries the semantics. The description's 'by id' adds nothing beyond that, making the baseline 3 appropriate.

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 verb and resource: 'Revoke an MCP key by id.' The MCP-key qualifier separates it from delete_api_key in the sibling list, though the description never explicitly contrasts the two, so it stops short of full sibling differentiation.

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 precondition for use with 'The key used for the current session cannot be revoked here,' which tells the agent when this call will fail. It offers no routing guidance toward delete_api_key or create_mcp_key alternatives, so it is context without exclusions.

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