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

Annotations already declare destructiveHint=true, but the description adds genuine value beyond that by spelling out irreversibility ('cannot be undone') and that it modifies live data. It does not cover auth requirements, rate limits, or error behavior for nonexistent contacts, keeping it short of a 5.

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?

One tight sentence plus an endpoint reference; the destructive/irreversible constraint is front-loaded in capitals, and no sentence is wasted.

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-parameter destructive tool with no output schema and annotations covering the safety profile, the description supplies everything needed to call it correctly, including both id formats. Minor gaps remain around error handling and required permissions.

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% and the contact_id description in the schema is nearly identical to the description text ('MD5 hash of the lowercased email address, or the id from list_contacts'). The description adds no meaning 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?

States a specific verb and resource with scope ('PERMANENTLY REMOVES a contact from a list'), which immediately separates it from get_contact, update_contact, and create_contact. The API endpoint mapping (DELETE /lists/{list_id}/contacts/{contact_id}) removes any ambiguity about what operation is performed.

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?

Clearly signals when this tool applies and warns that it 'cannot be undone,' which functions as a strong when-to-be-cautious cue. It stops short of naming alternatives (e.g., update_contact for unsubscribing instead of deleting), so it is clear context without explicit exclusions.

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