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

The description explicitly flags 'MUTATES Quaderno data', which is consistent with the destructiveHint annotation and adds the endpoint (POST /contacts) and the return behavior ('Returns the created contact'). It doesn't cover auth requirements, rate limits, or duplicate-handling, so it stops short of the richest disclosure.

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?

A single tight paragraph that front-loads the mutation warning, then the required-vs-optional split, then the endpoint and return. No redundant restating of the name or title.

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 create tool with 8 params, one required enum, and a nested object, it supplies the mutation flag, the required argument, the fields escape hatch, the endpoint, and the return value. Missing only edge-case behavior (duplicates, permission needs), which is a minor gap.

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 the baseline is 3, but the description adds real value by enumerating which additional attributes can go in the `fields` escape hatch (phone_1, region, postal_code, tax_status, discount, etc.), which the schema's generic nested-object definition does not spell out.

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 ('create a contact') and clarifies the scope ('customer or vendor'), making it clearly distinguishable from quaderno_get_contact, quaderno_list_contacts and quaderno_update_contact. An agent can identify this as the creation entry point without opening the 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?

It explains how to supply arguments ('Provide kind plus a name; use `fields` for any other attribute') but gives no explicit when-to-use guidance against siblings, e.g. no instruction to use quaderno_update_contact for existing contacts or to look up first. Usage context is implied rather than stated.

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