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

Annotations only declare idempotentHint=true, so the description must carry most of the burden. 'WRITE: it changes the record' usefully discloses mutation and the partial-update merge behavior is a valuable non-obvious trait. Beyond that, nothing is said about reversibility, permission needs, or error behavior for a 12-field mutation.

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 tight sentences with the mutation warning front-loaded and no filler. Appropriately sized for the sparse information it actually conveys.

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 12 parameters at 8% schema coverage, no output schema, and minimal annotations, an agent lacks the field-level meaning needed to populate optional fields confidently. The description should at least explain what the commonly used fields accept, which it does not.

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 only 8%, so only contact_id has any documentation ('Quipu resource id (integer)'), and even that omits that it is required. The description says nothing about any of the 11 optional fields, the document_type enum, or country_code's 2-character constraint, leaving most parameters semantically thin.

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 ('Update fields of one contact'), which clearly separates it from quipu_create_contact and quipu_get_contact. It does not explicitly name siblings, but the write/read/create distinction is inferable from the verb.

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?

The clause 'only the fields you send change' implicitly tells the agent this is a partial update, which is useful usage context. However, there is no explicit guidance on when to use this vs. create_contact, no prerequisites (e.g., contact must exist), and no mention of what happens on invalid IDs.

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