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

Annotations already cover the safety profile (readOnly, idempotent, closed-world), and the description adds real value on top: it lists what fields come back and explicitly warns that phone and e-mail are not included but live on the linked page, which changes how an agent should plan follow-up calls. It does not cover error behavior for an invalid id/URL.

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?

The field list and the phone/e-mail caveat are front-loaded in a single dense sentence with no filler. The appended Polish half-title 'Profil jednej firmy' is redundant with the tool title but is minimal.

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 an output schema present, the description need not explain return shape, and it nonetheless signals field coverage and the phone/e-mail gap. What remains unstated is that one of the two optional-looking parameters must actually be provided for a successful lookup.

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%, including an example id and example URL, so the schema already carries the parameter meaning. The description only restates that lookup is by id or page URL, adding no format or precedence guidance (e.g. which wins if both are supplied).

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 (fetch one Polish business profile) plus the two lookup keys (id or samiswoi.app page URL), and enumerates the returned fields. The word 'One' distinguishes it from list-style siblings such as search_companies.

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?

Usage is implied: a single-record lookup keyed by an id that the schema says comes from search_companies, so the search-then-fetch flow is inferable. However, the description never explicitly says when to use this versus search_companies, nor that exactly one of id/url should be supplied (the schema marks neither required).

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