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

Annotations declare non-readOnly, non-destructive, non-idempotent, which is a somewhat odd mix for a status/cancel tool. The description adds real value beyond that: it states the operation is free, that cancel takes effect immediately with no refund, and it enumerates the returned status fields (active state, expiry, delivered count, last delivery error). That is meaningful behavioral disclosure, though it doesn't address auth failure or idempotency of repeated cancels.

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, front-loaded with the key qualifier ('Free, no payment needed') before the mechanics. Dense but every clause carries information; only the long enumeration of return fields makes it slightly heavy.

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?

With no output schema, the description compensates by listing what the status call returns (active, expiry, delivered count, last delivery error) and by clarifying the destructive-looking cancel path is refund-free. Nothing an agent needs to invoke this correctly is missing.

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 description coverage is 100%, so both required parameters and the cancel flag are already documented in the schema. The description corroborates the credential source and the cancel semantics but adds no format or edge-case detail beyond the structured fields, so the baseline 3 applies.

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 names a specific verb (check) and resource (SEC alert subscription), plus the secondary action (cancel), and contrasts with the sibling sec_alert_subscription by naming it as the source of the credentials. An agent can distinguish this from sec_alerts_peek and sec_alert_subscription without opening schemas.

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?

It states the prerequisites (subscription_id and signing_secret from sec_alert_subscription) and the trigger for the cancel path (set cancel: true). It doesn't explicitly say when not to use it or route to a different sibling for related tasks, but the context is clear.

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