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

The description discloses that the operation is a soft delete (deactivation) and preserves historical events, which adds valuable context beyond the annotations (idempotentHint, destructiveHint). It also mentions ownership enforcement, which sets behavioral expectations. Since annotations already cover safety profile, the description provides supplementary benefit.

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?

The description is two sentences long, front-loads the action, and each sentence provides necessary information without waste. It's concise and well-structured.

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 with no output schema and decent annotations, the description covers purpose, ownership, and the deactivation effect. It also ties to related tool recent_alerts, making it contextually complete.

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 a clear description of the id parameter ('returned by subscribe'). The description simply says 'by id' and doesn't add new parameter semantics beyond the schema. Per baseline, a 3 is appropriate because the schema does the heavy lifting.

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 uses the verb 'Cancel' with the specific object 'subscription by id', making the tool's purpose immediately clear. It also distinguishes itself from sibling tools like subscribe and list_subscriptions by indicating this is the cancellation counterpart.

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 clearly indicates the primary use case (cancel subscription) and adds an important condition (only own subscriptions). It doesn't explicitly mention alternatives, but the ownership constraint and deactivation behavior provide sufficient guidance. There are no exclusions or when-not-to-use instructions, but the context is evident from sibling tool names.

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