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

Goes beyond annotations by explaining ownership enforcement and the soft-deactivation behavior (deactivated, not deleted), with reference to historical events via recent_alerts. No contradictions with annotations (idempotentHint=true, destructiveHint=false).

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 sentences, front-loaded with purpose, followed by critical constraints and behavior. No superfluous 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 simple one-parameter tool without output schema, the description covers purpose, constraint, and behavioral consequence completely, even linking to a related tool (recent_alerts). No gaps.

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?

Input schema already describes the 'id' parameter as uuid from subscribe. Description merely restates 'by id' without adding syntax or format details. Schema coverage is 100%, so 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?

Description states 'Cancel a subscription by id' with specific verb and resource. Ownership and deactivation behavior further clarify purpose, distinguishing it from siblings like 'subscribe' and 'list_subscriptions'.

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?

Clearly states ownership enforcement (only cancel own subscriptions) and that deactivation is soft (not deletion), implying appropriate use cases. Lacks explicit comparison to siblings but provides sufficient context.

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