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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so safety is covered. The description adds real value by disclosing the return payload contents (linked companies with position, custom fields, remarks), which is the only return-shape information available since no output schema exists. It does not cover error/not-found behavior or permissions.

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 compact sentences, zero filler, with the payload enumeration front-loaded right after the verb. The trailing 'Teamleader: contacts.info' maps the tool to the underlying API method in a few words.

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 single-parameter read with no output schema, the description is nearly complete because it enumerates what comes back. The only gap is what happens when the id does not exist or is inaccessible, which an agent may need to plan around.

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?

Only one parameter with 100% schema description coverage including a UUID pattern, so the schema carries the semantics. The description implies lookup by a specific contact but adds nothing about the id format or behavior on invalid ids. Baseline 3 applies.

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 (fetch) and resource (one contact) and enumerates the payload scope: emails, telephones, addresses, linked companies with position, tags, custom fields and remarks. The 'one contact in full' framing makes it distinguishable from teamleader_list_contacts and teamleader_get_company without opening any 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?

Usage is implied by the required contact_id and the 'one contact' scope, so an agent can infer it is the lookup-by-id counterpart to the list tool. However, there is no explicit statement of when to prefer this over teamleader_list_contacts or what to do when the id is unknown.

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