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

With no annotations, the description carries the full burden. It discloses the provenance of the credentials (unsubscribe_url) and that the effect is stopping notices, but does not say whether the action is reversible, whether re-subscribing is possible, or what happens on an invalid signature.

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?

A single tight sentence with the action front-loaded and the parameter provenance appended. No wasted words, though it is arguably terse given the missing behavioral detail.

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 two-parameter unsubscribe tool with no output schema and no annotations, the description covers the essential action and credential source. It omits any post-action state (reversibility, confirmation) and error behavior, leaving minor 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?

Schema coverage is 100%, so the schema already documents both parameters. The description adds the origin of the pair ('from your unsubscribe_url'), which lightly clarifies usage but adds no format or validation detail beyond the schema's 'sub_...' and 'signature from the link'.

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?

States a specific verb (Stop) and resource (update notices), which clearly distinguishes it from the sibling subscribe_updates and get_updates. It stops short of explicitly naming the counterpart tool, but the intent is unambiguous.

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 parenthetical '(id + sig from your unsubscribe_url)' implies the trigger context: use this when you have an unsubscribe link. There is no explicit when/when-not guidance or mention of the alternative subscribe_updates, leaving usage only implied.

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