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

The destructiveHint=true annotation signals mutation, and the description adds real value beyond it by disclosing that contact_group_ids REPLACES the existing group set rather than merging it. It also names the underlying endpoint (PUT /contacts/{id}). It does not state permission requirements or confirm change reversibility, which keeps it from 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?

Three short, front-loaded sentences. The destructive REPLACES warning is placed prominently, and every sentence carries information with 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?

For a small three-parameter update tool with annotations covering the safety profile and a fully documented schema, the description is sufficient for correct invocation. It omits only peripheral details like error behavior on invalid group ids.

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 all three parameters are already documented, including the 'replaces the current groups' note on contact_group_ids. The description's REPLACES emphasis is helpful but largely duplicates the schema. 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 ('rename', 'set') and resource ('contact', 'contact groups'), so the agent knows exactly what the tool mutates. It is distinguishable from trengo_get_contact and trengo_create_contact by implication, though it never names a sibling explicitly.

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 'and/or' phrasing implies the tool is used when renaming or reassigning groups, which gives usable context. However, there is no explicit when-not guidance or mention of alternatives such as trengo_create_contact for new records.

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