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

Discloses ownership enforcement, deactivation vs deletion, and historical data preservation via recent_alerts. All behaviors are consistent with annotations (readOnlyHint=false, destructiveHint=false, idempotentHint=true), adding value beyond structured fields.

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, 33 words, front-loaded with primary action. Every sentence adds essential information: action, ownership constraint, and side effects. No wasted words.

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?

Completely describes the tool's purpose, constraints, and effects for a simple tool with one parameter and no output schema. The description is sufficient for correct selection and invocation.

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% (id described as 'Subscription id (uuid) returned by subscribe'). The description adds minimal extra meaning by referencing 'subscribe', but baseline of 3 is appropriate since schema already fully documents the parameter.

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 'Cancel a subscription by id', specifying the verb and resource. It distinguishes itself from sibling tools like 'subscribe' (creates) and 'list_subscriptions' (lists), and adds ownership enforcement.

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?

Provides clear context: ownership enforcement means only the owner should use it. Mentions that rows are deactivated, not deleted, directing users to recent_alerts for history. Lacks explicit when-not-to-use or alternatives.

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