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

Beyond annotations (destructiveHint=true, idempotentHint=true), the description discloses irreversibility, the account-wide blast radius, and the exception that the Rinkel system contact cannot be deleted. It also narrates the human-approval gate, which is the key behavioral constraint for a destructive tool.

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 sentences, each carrying distinct information: mutation class and scope, confirmation requirement, protected-record exception. The most decision-relevant fact (WRITE, irreversible) is first.

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, everything an agent needs to invoke it correctly is present: safety profile, scope, approval protocol, and the blocking edge case. Nothing essential is deferred to structured fields.

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 baseline is 3; the description adds value by constraining which contact_id values are valid (the system contact is rejected) and by reinforcing the semantics of the confirm flag as an approval gate rather than a generic boolean.

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?

Opens with a specific verb and resource ('delete a contact') qualified by scope ('for the whole account') and the exact API operation (DELETE /contacts/{id}). It is unambiguous against siblings like rinkel_update_contact or rinkel_get_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?

Gives a clear procedural precondition: confirm=true only after the user approved this exact action, which tells the agent when it may proceed. It does not, however, point to alternatives (e.g. update_contact) or describe when deletion is preferable to other resolution paths.

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