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

With no annotations, the description carries the full disclosure burden. It usefully states the source (Companies House advanced search) and the cost ('2 credits'), which is real context an agent cannot get elsewhere. It omits read-only confirmation, result shape, ordering, pagination/limit behavior, and whether exceeding limits truncates or errors.

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 compact fragments, front-loaded with the verb and resource, then filters, then API source, then use case and cost. Nothing is padded, though the sentence-fragment style ('New-business lead lists.') is slightly telegraphic.

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 7-parameter, no-annotation, no-output-schema search tool, the description covers what can be filtered and what it costs but not what comes back (fields, count, ordering) or how the limit interacts with total matches. An agent could invoke it, but not confidently predict or explain the output.

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 baseline is 3; parameters are already self-documented including the '["active"]' default for status and the 1-100 limit. The description adds meaning only at the aggregate level by naming which filters exist, without clarifying interactions such as whether filters are ANDed or how SIC codes are matched.

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?

The description gives a specific verb ('Find') plus the resource ('companies') and enumerates the filter dimensions (incorporation date range, SIC codes, status, location, name fragment), which lets an agent distinguish it from name-lookup siblings like company_search and record-detail siblings like company_profile/company_filings. It falls short of 5 only because no sibling is named directly.

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?

'New-business lead lists' implies the intended use case, and the filter list hints at what queries belong here. There is no explicit when-not guidance, no mention of when to prefer company_search or company_profile instead, and no prerequisites such as API key or coverage limits.

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