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

Annotations already set destructiveHint=true and readOnlyHint=false, indicating mutation. The description adds significant value by disclosing that the tool may either perform the unsubscribe directly or return a URL that requires human intervention. This goes beyond annotations and sets accurate expectations for safe usage.

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 with no wasted words. Every sentence adds essential behavioral context, including the conditional behavior of the server-side vs. human-intervention pathway.

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?

Given the tool's simplicity (one parameter, no output schema), the description covers all critical aspects: purpose, behavior, and two possible outcomes. It slightly lacks explicit mention of return format (e.g., does it return a string URL?) but is otherwise complete for a straightforward operation.

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 single parameter is already documented in the schema. The description does not add any additional meaning or usage details for the newsletter_id parameter beyond what the schema provides, so a baseline of 3 is appropriate.

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 a specific verb 'Unsubscribe' and resource 'newsletter', clearly distinguishing it from sibling tools like 'delete_source' or 'add_feed'. It also clarifies the domain ('arriving in one of the inboxes'), making the tool's intent 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 description provides clear context on when to use it (to unsubscribe), and transparently explains two behavioral scenarios: direct server-side unsubscribe vs. returning a URL for manual action. It does not, however, explicitly contrast with alternatives like 'delete_source' or suggest when not to use this tool.

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