entity_lookupThe Wen Receipts register entry for a firm, by its register identifier (scheme + value, e.g. lei) or by the slug of its page. Exact match; returns the whole record with its page.
| Name | Required | Description | Default |
|---|---|---|---|
| slug | No | ||
| value | No | ||
| scheme | No | identifier scheme, e.g. lei, fca_frn, tdlr_license |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden and does add useful traits: exact-match semantics and that it returns the whole record plus its page. It omits error/not-found behavior, auth or rate-limit constraints, and the priority when both slug and scheme+value are supplied. Useful but incomplete for a zero-annotation tool.
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 tight sentences, front-loaded with the resource and identifier mechanics. No filler, though the trailing 'returns the whole record with its page' could be folded more cleanly.
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 3-param lookup with no annotations and no output schema, the description usefully covers both how to address the entity and what comes back. The remaining gap is the mutual-exclusivity/priority of slug vs scheme+value and not-found behavior, but the core need is met.
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 only 33% (solely 'scheme'), so the description must compensate, and it partially does by explaining that 'scheme + value' form the register identifier and that 'slug' is an alternative route (e.g. 'lei'). It does not clarify that none of the three are schema-required while effectively one mode or the other must be supplied, nor address the length constraints.
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 ('register entry for a firm') and clearly scopes it to a single entity, with the 'Exact match' qualifier implicitly separating it from the search-oriented siblings like entities_search. The two accepted access paths (register identifier or page slug) are named. It doesn't explicitly call out the sibling it is not, so it falls just short of a 5.
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?
'Exact match' hints that this is for when you already hold a precise identifier rather than for discovery, which implies entities_search is the alternative. However, it never states when to use this vs. the sibling search/list tools, nor prerequisites. Usage is implied rather than stated.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.