entity_lookupThe Immigration Adviser Finder 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 burden and does disclose that matching is exact and that the whole record plus its page is returned. It is silent on the not-found/error case and on the fact that slug and scheme+value are alternative (not cumulative) lookup paths, which is behavior an agent needs.
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; the resource and its two lookup keys are front-loaded, and no clause is redundant.
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 no-annotation, no-output-schema lookup, it covers the key inputs and the return shape ('whole record with its page'), but leaves the mutually exclusive use of slug vs. scheme+value and the failure behavior unaddressed.
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% (scheme is the sole documented parameter), so the description must compensate, and it does by explaining that 'value' is the identifier value paired with 'scheme' (e.g. lei) and that 'slug' addresses the entity's page. This adds real meaning beyond the bare schema types.
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 Immigration Adviser Finder register entry for a firm, keyed either by register identifier (scheme + value) or by page slug. This clearly separates it from the entity listing/search siblings, though it does not name any sibling explicitly.
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' implies the tool is for when you already hold a known identifier or slug, which contrasts with searching, but that contrast is never made explicit and no alternative such as entities_search is named. Usage is therefore only implied.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.