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

With no annotations, the description carries the full burden, and it delivers the most surprising trait: an existing address returns the existing contact rather than erroring, so the call is idempotent/upsert-like. It does not disclose permissions required, what happens to supplied fields when a matching contact is found, or what the response contains — meaningful gaps for a 9-parameter write.

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, zero waste, with the core purpose first and the idempotency consequence second. Nothing is padded or restated.

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 9-parameter creation tool with no annotations and no output schema, the description covers purpose and idempotency but leaves the key operational question unanswered: if the address already exists, are the other eight supplied fields applied, merged, or discarded? An agent cannot predict the outcome of a duplicate call with populated optional fields.

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 coverage is 100%, so all nine parameters are already documented in the schema, and the description only echoes that the email identifies the fiche. That echo is useful but adds little beyond the schema's own wording; 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 ('opens a fiche') and resource (contact), and scopes it to 'before any exchange has happened', which tells an agent this is a pre-interaction contact creation rather than an update after correspondence. It never names get_contact/update_contact as the alternatives, so sibling differentiation relies on the tool name rather than the prose.

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?

'Before any exchange has happened' gives a clear triggering context, and the idempotency note tells the agent it's safe to call without first checking existence. Missing is guidance on when to prefer update_contact or get_contact instead of re-calling this tool.

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