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

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so safety is covered; the description adds value by detailing the return payload, including attribution semantics (latest touch, origin, ad title and Meta id). It does not discuss side effects or rate limits, but none are expected for a read 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?

Two sentences, front-loaded with the verb and resource, then the return contents, then the id-sourcing hint. Given there is no output schema, the field enumeration earns its space.

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?

Because no output schema exists, the description appropriately enumerates the returned fields and attribution structure, and the input schema carries error semantics. Only the structural shape of nested attribution objects is left slightly implicit.

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?

With 100% schema coverage the baseline is 3, but the description adds provenance semantics for contact_id that the schema does not provide. agent_id semantics are left entirely to the schema, which is acceptable.

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 ('Get one contact of an agent') and enumerates the exact fields returned, which distinguishes it clearly from list_contacts and from get_lead. An agent can tell precisely what it gets back without opening a schema.

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 tells the agent where to obtain the required contact_id ('from list_contacts or from a lead's contact_id'), which is real routing guidance. It lacks an explicit when-not condition (e.g. use list_contacts for bulk retrieval), so it falls short of a 5.

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