Find Yahoo Finance instruments by ticker or company name, with optional filters for type like equity, ETF, or crypto.
Yahoo Finance lookup. Returns Yahoo Finance instrument matches for a query, optionally filtered by instrument type.
| Name | Required | Description | Default |
|---|---|---|---|
| type | No | Instrument type filter | |
| count | No | Result count | |
| query | Yes | Ticker symbol or company name | |
| start | No | Result offset |
Changes observed during successful MCP inspections.
v1.17.5Input schema / properties / type / enumAdded value: +[
+ "all",
+ "equity",
+ "etf",
+ "mutualfund",
+ "index",
+ "future",
+ "currency",
+ "cryptocurrency"
+]v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden of behavioral disclosure. It mentions that results are 'matches' and that type filtering is optional, but it does not describe whether matching is fuzzy or exact, how pagination works via start/count, or what fields a match contains. This is thin for a tool searching a large external data source.
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 short sentences; the core behavior appears in the second sentence. The opening phrase 'Yahoo Finance lookup' is near-tautological, but the overall text is efficient and front-loaded with the essential action.
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 and no annotations, the description should supply more context about what constitutes a match, what the returned data looks like, and how to page through results. It is enough for a trivial lookup, but it leaves gaps an agent would have to infer when choosing among many sibling Yahoo Finance tools.
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 100% — every parameter has a description, so the baseline is 3. The description adds only the notion of 'optionally filtered by instrument type,' which largely overlaps with the type parameter's own description. No additional meaning is provided for query, count, or start.
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 uses a specific verb ('Returns') and resource ('Yahoo Finance instrument matches') and notes the optional type filter. It clearly indicates this is an instrument search/lookup tool, though it doesn't explicitly distinguish it from sibling tools like yahoo_finance_search or yahoo_finance_ticker_quote.
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?
No guidance on when to use this tool versus alternatives such as yahoo_finance_search, yahoo_finance_screener, or yahoo_finance_ticker_quote. The 'optionally filtered by instrument type' phrase gives some context but no exclusions or decision criteria.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.