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

Annotations already cover safety (readOnly, idempotent, closed-world), so the description's job is incremental. It delivers real value by disclosing the return scope ('identity only, no figures') and warning that a bank holding company (CIK) and its operating bank (RSSD) are distinct entities — a non-obvious disambiguation that no annotation conveys. It stops short of stating error behavior for unresolvable names.

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?

Purpose is front-loaded in the first sentence, followed by usage, identifier syntax, and follow-up routing in a logical order. Every sentence carries information, though the dense parenthetical ID list and the level warning make the block slightly heavy for a single-parameter tool.

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 output schema, the description steps in to describe what comes back (entity plus CIK/LEI/EIN/UEI/RSSD anchors) and what it deliberately omits (figures). Combined with the follow-up guidance and the entity-granularity warning, an agent has everything needed to call this correctly and chain it.

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 0% and the schema provides no description, so the description must carry the full load — and it does, documenting the accepted identifier prefixes ('cik:0000936468', 'lei:...', 'ein:...', 'uei:...', 'qid:Q7240') and the preference for IDs over names. This is meaning that exists nowhere in the structured fields.

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: 'Resolve a US company, bank or nonprofit to its registry entity.' It also names what the result contains (registry anchors) and explicitly separates itself from get_facts/get_timeseries, which only return figures. An agent can distinguish it from every sibling without opening a schema.

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?

Gives the triggering condition ('when you have a name, ticker context or an identifier'), a tie-break rule ('IDs beat names' with concrete formats), and the follow-up path ('follow up with get_facts or get_timeseries using the returned entity id'). When/when-not and alternatives are all explicit.

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