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

Annotations already declare readOnlyHint=true, so safety is covered. The description adds useful context that results include account balance and identifies the underlying endpoint (GET /v2/contacts), but says nothing about pagination behavior or default result window beyond what the schema provides.

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 sentence plus an endpoint reference, front-loaded with the core action and resource. No filler; every clause earns its place.

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 read-only list tool with a fully documented schema, most of what is needed is present. However, there is no output schema and the description only hints at one returned field (account balance), leaving the shape of each contact record largely unspecified.

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% with detailed enum descriptions (view, sort) and pagination bounds, so the schema carries the parameter burden. The description adds no parameter meaning beyond that, making baseline 3 appropriate.

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 ('List contacts (clients and suppliers)') and adds the returned field ('account balance'), which separates it from sibling get_contact / create_contact / update_contact. It does not explicitly name a sibling or scope limitation, so it falls short of a 5.

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?

No statement of when to use this versus get_contact (single record), or when to prefer a filtered view. Usage is only implied by the verb 'List'. The schema's view enum hints at filtering scenarios, but the description itself provides no guidance.

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