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

Annotations already declare destructiveHint=true and idempotentHint=true, so the safety profile is covered; the description adds the genuinely non-obvious semantics that messages, consent records and topic preferences survive the delete. It doesn't say whether the delete is reversible or what happens when the id doesn't exist.

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 sentences, action first and the non-obvious retention caveat second. Nothing wasted, nothing buried.

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 single-id destructive tool with full annotation coverage and no output schema, the description supplies the one piece of behavior annotations can't express (data retention). Minor gaps remain around failure behavior and reversibility.

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% for the single required parameter ('id': 'Contact id'), so the schema carries the parameter burden. The description adds no format or sourcing detail beyond it, which is the baseline case.

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 ('Delete a contact'), which cleanly separates it from delete_message, delete_list, delete_customer and the other delete_* siblings. It stops short of naming any sibling explicitly, so it is clear but not differentiating in prose.

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?

There is no 'when to use this instead of X' guidance: an agent must infer from sibling names whether delete_contact or forget_identity is the right call for removing a number's data. Only the retention sentence hints at a use case (keeping history while removing the contact).

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