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

Annotations already declare destructiveHint=true and idempotentHint=true, and the description reinforces this with 'no undo for this' and the irreversible master-unsubscribe scope — critical context beyond the flags, especially the permanence and the master-list effect.

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?

Three short clauses, front-loaded with WRITE label and the destructive consequence, then the endpoint. Every sentence earns its place.

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 2-param write tool with no output schema, the description fully conveys the irreversible effect and the endpoint. It's essentially complete; only the alternative-tool routing could be tightened.

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 parameters (list_id, contact_id) are fully documented with patterns and provenance hints. Description references the endpoint path shape, adding minor reinforcement but nothing beyond the schema.

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+resource (move a contact to the Do Not Contact list) with precise scope ('master unsubscribe'), which clearly distinguishes it from siblings like benchmark_update_contact and benchmark_add_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?

Context clarifies when this applies — preventing any future campaign from reaching the contact. However, it doesn't explicitly compare against the sibling benchmark_update_contact (which might also set contact status), so the alternative selection isn't spelled out.

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