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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=false. The description adds real value beyond that: it discloses the write side effect explicitly and warns that the optional 'shared' flag exposes the group to corporate members — a consequence not encoded in any structured field.

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, front-loaded statements: purpose, integration rule, side effects. No filler, and the most decision-relevant information (the name-not-id rule) appears early.

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?

An output schema exists, so return values need no explanation. Combined with annotations covering the safety profile and the description covering side effects and the name-vs-id rule, an agent has enough to invoke it correctly; only parameter validation details are missing.

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 0%, so the description must compensate. It meaningfully explains the effect of 'shared' (disclosure to corporate members), which is the least obvious parameter, but leaves 'name' and 'notes' unelaborated (e.g., uniqueness constraints, length limits, whether notes are visible to other members). Partial compensation only.

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 ('Create a contact group') and clarifies the domain concept by equating it with a 'Fax.Plus tag' used to organize contacts, which distinguishes it from sibling tools like update-contact-group or set-contact-groups.

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 concrete downstream usage rule — when assigning contacts via set-contact-groups / create-contact / update-contact, pass the group's name rather than its id — which names the exact sibling tools involved. It stops short of saying when to create a group versus when to reuse an existing one via list-contact-groups, but the guidance is clear and actionable.

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