entity_lookupThe Bags That Pay 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?
No annotations are provided, so the description carries the full burden. It usefully discloses exact-match semantics and that the whole record plus its page is returned, but it says nothing about not-found behavior, precedence when both lookup modes are supplied, or whether an empty argument set errors out.
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?
A single dense sentence that front-loads the resource and then the two input modes. Nothing is wasted, though the nested parenthetical makes it slightly harder to parse at a glance.
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 annotations and no output schema, the description does cover both input routes and roughly what is returned, but omits not-found handling, mutual exclusivity of the two modes, and the fact that at least one route must be supplied despite zero required parameters.
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%, but the description compensates by explaining the two lookup modes and the important relational semantics: scheme + value together form the register identifier, while slug is an alternative page-based lookup. This is meaning the bare schema does not convey.
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: fetching the register entry for a firm by register identifier or page slug. It is clear and unambiguous, though it does not name or contrast itself with the sibling it is most likely confused with, entities_search.
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?
The phrase 'Exact match' implies this is for exact lookups rather than the query-style retrieval that entities_search presumably offers, so usage is implied but never stated directly. There is no explicit 'use X instead when Y' guidance or mention of prerequisites.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.