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

readOnlyHint already declares this as a safe read, but the description adds genuinely new behavioral context: the fair-use quota (1000/day, 31000/month) and the fact that every tool call consumes one request. It stops short of explaining response shape or error behavior, so not 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?

Front-loaded with the resource, then the quota context, then the all_companies branch. Dense but every sentence carries information; the parenthetical quota detail is slightly verbose but earns its place by preventing accidental rate-limit exhaustion.

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 no output schema, the description compensates by enumerating returned fields, and it covers the rate-limit behavior an agent needs to budget calls. Nothing essential for correct 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 coverage is 100%, so the baseline is 3, but the description goes further by explaining the consequence of all_companies=true and that returned ids correspond to the login's company_id. That adds meaning beyond the schema's one-line definition.

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+resource (retrieves the company profile the API key operates in) and enumerates the returned fields (name, IČO, DIČ, IČ DPH, address, VAT flag, bank accounts) plus remaining quota. This clearly separates it from siblings like superfaktura_get_client or superfaktura_get_invoice.

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?

"Good first call" gives explicit guidance on when to reach for it, and the all_companies branch tells the agent when to widen scope. It does not name a specific alternative tool or state exclusions, so it falls short of a full 5.

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