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

Annotations only declare readOnlyHint and openWorldHint, so the description carries the interesting burden and does add real context: it discloses the event model (attribute_changed events, first-observed semantics, effective_from temporal bounds, evidence per event). Since there is no output schema, this return-shape disclosure is genuinely valuable. It still omits ordering and pagination behavior, and the presence of `limit` implies paging that is never explained.

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 short sentences, zero filler, and the core capability is front-loaded before the optional filter and return-shape notes. Every clause carries information.

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 3-parameter tool with full schema coverage and no output schema, the description covers purpose, event semantics, filtering, and return content. The remaining gap is paging/ordering behavior implied by the limit parameter, which an agent calling this tool would want to know.

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 the schema already documents all three parameters, including the limit default/max and the organisation_number format. The description only restates the optional attribute_key filter and adds no syntax or semantics beyond it. Baseline 3 applies when the schema does the heavy lifting.

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 ('Retrieve the change history for a Swedish company') and narrows the content to 'attribute_changed events showing when values were first observed and what changed', which is far more precise than the bare name. It does not explicitly contrast itself with siblings like get_company or search_company_events, so the agent must infer the boundary, but the scope is unambiguous on its own.

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?

There is no statement of when to pick this over get_company (current state) or search_company_events (event search). 'Optionally filter by attribute key' is parameter guidance, not tool-selection guidance. The agent is left to infer the use case entirely from the purpose sentence.

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