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

Annotations already provide idempotentHint and non-destructive hint. Description adds context beyond: ownership enforcement, row deactivation (not deletion), and preservation of historical events. No contradiction with annotations.

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, no extraneous words. Each sentence provides critical information: action, ownership constraint, and side effects.

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-param tool with no output schema, the description covers purpose, prerequisites (ownership), behavioral effects (deactivation), and data persistence. 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?

Schema already describes id as a UUID from subscribe (100% coverage). Description merely restates 'by id' without additional constraints or format details. Baseline 3 is appropriate as schema does the work.

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', and distinguishes from sibling tools like 'subscribe' and 'list_subscriptions' by noting ownership enforcement and the deactivation effect.

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 usage condition: ownership enforced (only own subscriptions). Also explains the behavioral nuances (deactivation vs deletion) helping agents decide when to use this tool, though no explicit alternatives are mentioned.

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