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

Beyond annotations ('destructiveHint': false, 'idempotentHint': true), the description adds critical behavioral detail: 'The row is deactivated (not deleted) so its historical events stay available via recent_alerts.' This clarifies the exact side effect and historical data retention.

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 concise sentences that front-load the action and key constraints. No extraneous words; every sentence adds value.

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 tool with one required parameter, no output schema, and moderate annotations, the description fully covers the operation's purpose, ownership restriction, and side effect (deactivation vs deletion). No gaps remain.

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?

The single parameter 'id' is fully documented in the input schema with description 'Subscription id (uuid) returned by subscribe.' The description does not add further semantic meaning beyond referencing the sibling tool, which is sufficient given 100% schema coverage.

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 starts with a clear action verb 'Cancel' and the resource 'subscription by id'. It immediately distinguishes from siblings like 'subscribe' and 'list_subscriptions' by specifying the reverse operation.

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?

The description provides an important usage condition: 'Ownership is enforced — you can only cancel your own subscriptions.' This helps the agent decide when to invoke the tool, though it does not explicitly mention when not to use it or alternatives.

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