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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds real behavioral value by disclosing the error-reporting contract: a missing or wrong answer surfaces in a "problem" field naming the question, which an agent needs in order to retry correctly.

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 sentences with the prerequisite and the return contract front-loaded; nothing is padding. The opening clause is a sentence fragment ("At the company chosen from find_companies (pass its company)") that reads awkwardly, but it is still efficient.

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 read-only calculator with a nested answers object and no output schema, the description covers the essentials: inputs' provenance, the returned price/duration, and the "problem" validation output. It could say more about how units/answers interact for counted services, but nothing critical to invocation is missing.

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 five parameters (including lang, units, and the nested answers object) are already documented. The description's note that answers are checked against the service's questions echoes the schema rather than adding new semantics — 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 and outcome: it checks the client's answers and returns price and duration. It also names its upstream dependency (find_companies) and the failure field ("problem"), so an agent can tell exactly what this tool produces versus siblings like list_services or book_appointment.

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?

Implies the required workflow order by saying the company comes from find_companies and the service key from list_services, which is genuine when-to-use guidance. It does not state any exclusions (e.g., that it does not reserve a slot — use book_appointment for that), so it falls short of a 5.

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