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

Annotations cover the safety profile (idempotent, non-destructive write), and the description adds genuinely new behavioral information: that a wildcard must terminate the value and include a country code, and that a broad wildcard blocks every caller from an entire country — a real blast-radius warning. The endpoint reference is a bonus for debugging.

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 dense sentences, each doing distinct work: operation and scope, accepted value forms and their risks, undo path plus endpoint. Front-loaded with the WRITE marker and no filler.

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 two-parameter mutation with no output schema, everything an agent needs is present: accepted input forms, wildcard edge cases, reversibility, and the API surface. Nothing material is omitted.

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 earns a bump by elaborating wildcard semantics beyond the schema's one-line hint — the 'must end the value' and 'broad wildcard blocks a whole country' constraints are not apparent from the schema alone.

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 ('block a number') plus the exact scope ('from calling ANY of the account's numbers'), which distinguishes it cleanly from the many read/list siblings. The 'WRITE:' prefix further signals mutation at a glance.

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?

Explicitly routes the agent to rinkel_unblock_number as the inverse operation, giving clear when-to-use context. It stops short of naming prerequisites (e.g., whether the number must first be validated via rinkel_validate_phone_number) or exclusions, so not quite a 5.

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