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

Annotations already declare readOnlyHint=false, destructiveHint=true, idempotentHint=true, so the safety profile is covered. The description adds real context beyond that: the operation is destructive to list membership only, not to the contact, and it is a POST to a specific endpoint. It does not say what happens if the contact is not on the list, but the added scope clarification is meaningfully more than the annotations provide.

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 short clauses, front-loaded with the WRITE marker and the key scope caveat. The endpoint path is somewhat visible-implementation noise but is compact and arguably useful for API-aware agents.

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 3-parameter mutation with full schema coverage and rich annotations, the description plus structured fields give an agent enough to call it correctly. Only edge-case behavior (contact not on the list, list not found) is undocumented, which is a minor gap.

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 email/member_id alternation and the sub_list_id source are already documented in the schema. The description adds no parameter-level detail, which is the expected baseline when the schema does the work.

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 and resource (take a contact off one list) and adds the crucial scope note that the contact record itself is kept, which separates it from delete/unsubscribe semantics. It does not name a sibling tool, but the distinction is implied clearly enough to pick between this and robly_unsubscribe_contact.

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 'the contact itself is kept' implies the appropriate scenario for this tool, but there is no explicit when-to-use or when-not guidance versus robly_unsubscribe_contact or removing a contact entirely. Sibling differentiation is left to inference.

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