Look up a public company's CIK (Central Index Key) by ticker symbol or company name. CIK is required for all other EDGAR tools. Returns matches ranked exact-ticker first.
| Name | Required | Description | Default |
|---|---|---|---|
| limit | No | Maximum rows to return (default 25, max 100). | |
| query | Yes | Ticker (e.g. 'AAPL') or company-name fragment (e.g. 'Apple'). |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover read-only, idempotent, and non-destructive behavior. The description adds useful behavioral context beyond annotations: matches are ranked exact-ticker first, and the lookup supports both ticker and name fragments. This gives the agent a clearer expectation of results without contradicting the annotations.
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 sentences, no filler, with the core lookup purpose and key ranking behavior stated directly. The most important context—that CIK is the prerequisite for other EDGAR tools—is included early and efficiently.
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 simple two-parameter lookup with no output schema, the description covers what the tool does, how queries are matched, and how results are ordered. It does not detail the exact result fields, but the purpose is clear enough that an agent can invoke it correctly.
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 schema already documents both parameters in detail. The description reinforces the query semantics by mentioning ticker or company name, but adds limited additional parameter-level meaning beyond what the schema provides.
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 states a specific action—look up a public company's CIK—by ticker symbol or company name. It also establishes how this tool relates to the other EDGAR tools, distinguishing it as the prerequisite lookup rather than a filings or facts tool.
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 'CIK is required for all other EDGAR tools' clearly communicates when this tool should be used: as the entry point for EDGAR workflows. It does not explicitly name sibling alternatives or state when not to use it, but the context is sufficient for an agent to route correctly.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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