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 the useful payload detail (name, email, phone, custom field data, optional notes), which substitutes for the missing output schema. It does not mention permission requirements or behavior when the id does not exist, keeping it short of a 5.

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 terse sentences, the return payload front-loaded and the API mapping trailing as useful metadata. 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?

With no output schema, the description usefully summarizes the returned fields, which is what an agent needs for a simple point lookup. It stops short of covering error/not-found behavior or whether custom fields are always populated.

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%, so both parameters are already documented in the schema; the description's 'optionally with notes' merely restates include_notes. Baseline 3 is correct when the schema carries parameter semantics.

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 singular resource (one contact), enumerates the returned fields, and maps to the concrete API call GET /contacts/{id}. The singular scope clearly distinguishes it from the sibling trengo_list_contacts.

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 only implied: the singular 'one contact' plus the required contact_id signal this is a point lookup rather than a listing. There is no explicit statement of when to use this instead of trengo_list_contacts or how it relates to trengo_update_contact.

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