Fetch Yahoo Finance ETF or mutual fund data for a ticker like SPY, including profile, top holdings, equity, bond, and sector weightings.
Yahoo Finance fund data. Returns fund data for an ETF or mutual fund symbol such as SPY, under modules: the fund profile, top holdings, equity holdings, bond holdings and sector weightings.
| Name | Required | Description | Default |
|---|---|---|---|
| symbol | Yes | Yahoo Finance symbol such as SPY |
Changes observed during successful MCP inspections.
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 behavioral burden. It helpfully discloses the payload shape (fund profile, top/equity/bond holdings, sector weightings), but says nothing about rate limits, auth needs, error behavior, or the important constraint that data only exists for funds (not regular stocks). The phrase 'under `modules`' is also ambiguous since no `modules` parameter exists.
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, front-loaded with the resource and scope, with zero filler. The 'under `modules`' clause is the only slightly murky part, but the overall structure is efficient.
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 compensates reasonably by enumerating the returned modules and flagging the fund-only applicability. It is adequate for a single-parameter read tool, though it omits behavioral context an agent might want before calling.
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% for the single `symbol` parameter, so the schema already documents it. The description's example (SPY) and the ETF/mutual-fund restriction add a little meaning but do not go beyond the schema baseline.
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 (returns) and resource (fund data for an ETF or mutual fund symbol like SPY), and enumerates the modules returned, which makes the scope concrete. It does not explicitly name or differentiate itself from near-neighbors such as yahoo_finance_ticker_info or yahoo_finance_ticker_holders, so an agent must infer the split from the name and module list.
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 description says what the tool returns but gives no when-to-use guidance, prerequisites, or alternatives. It never tells the agent when to pick this over yahoo_finance_ticker_info or yahoo_finance_ticker_holders despite heavy sibling overlap.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.