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

Adds value beyond annotations: ownership enforcement, deactivation (not deletion), and historical event availability via 'recent_alerts'. Annotations already indicate non-destructive, idempotent mutation; description confirms and expands. No contradiction.

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 sentences, 20 words. Front-loaded with action and purpose. No redundancy. Every sentence is necessary and informative.

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?

Given single parameter, no output schema, and simple behavior, the description fully covers ownership, state change, and relation to 'recent_alerts'. Complete for an agent to select and invoke correctly.

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% with description for 'id' parameter. Description adds context that id is 'returned by subscribe', which is helpful but not extensive. Baseline 3 is 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 clearly states the verb 'Cancel' and the resource 'subscription by id'. It distinguishes from siblings by mentioning ownership enforcement and deactivation vs deletion, and references 'recent_alerts' for historical events, providing specific scope.

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?

Explicitly states ownership enforcement ('you can only cancel your own subscriptions'), guiding when to use. Mentions deactivation (not deletion) and links to 'recent_alerts' for historical data, implying when not to use. Does not explicitly name sibling alternatives, but context is sufficient.

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