Check if a Yahoo Finance market such as US is open or closed. Provide a market code to get its current status, name, and trading state.
Yahoo Finance market status. Returns whether a Yahoo Finance market is open or closed, for the path market such as US. The response has market and a status object with the market id, name and its current open or closed state.
| Name | Required | Description | Default |
|---|---|---|---|
| market | Yes | Market such as US |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations exist, so the description carries the burden. It does disclose the response shape (a `market` field plus a `status` object with id, name, and open/closed state), which is genuinely useful with no output schema. However it says nothing about auth needs, rate limits, or what happens for an invalid market path.
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?
Three short sentences, purpose front-loaded, no filler. Slightly more verbose than necessary in restating the response contents, but every sentence is on-topic and readable.
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 one-parameter read tool with no output schema, the description explains both input form and return structure, so an agent can call it and interpret results. The remaining gap is the absence of any guidance on error cases or invalid market values.
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% and there is a single required parameter, so the schema already documents `market`. The description reinforces the format with the `US` example but adds no meaning beyond the schema, matching the baseline of 3.
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+resource: returns whether a Yahoo Finance market is open or closed. The scope (a single market path like `US`) is clear and an agent can tell it apart from market_summary or calendars. It stops short of naming siblings explicitly, so it is not a 5.
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 when-to-use or when-not-to-use guidance is given, and no alternative tool (e.g. yahoo_finance_market_summary) is named. Usage is only implied by the nature of the resource, which leaves routing to inference.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.