stock_why_movingExplains why a stock ticker moved using Finviz data, returning a headline, summary, sentiment, and catalyst flag to clarify price action.
Finviz's own explainer for why a ticker moved (Finviz-only).
Args: symbol: Ticker.
Returns:
Envelope labelled FINVIZ with headline, summary, sentiment and
catalyst flag.
| Name | Required | Description | Default |
|---|---|---|---|
| symbol | Yes |
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are supplied, so the description carries the burden. It usefully discloses the data source (Finviz only) and the returned fields, but says nothing about coverage limits, behavior when Finviz has no explainer, or freshness of the catalyst data.
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?
The core purpose is front-loaded in one clear sentence, and the Args/Returns block is short. The docstring-style formatting is slightly mechanical but nothing is padded.
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?
An output schema exists, so the Returns summary is a bonus rather than a necessity. For a single-parameter read tool this is close to adequate, but the absence of any guidance on alternatives or empty-result behavior leaves a gap.
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 0% and the description only says 'symbol: Ticker.', which essentially restates the schema title. No format guidance (exchange suffix, case, ambiguity between tickers) is added, so it fails to compensate for the coverage gap.
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: it retrieves Finviz's own explanation for why a ticker moved. The '(Finviz-only)' qualifier signals the data source and implicitly distinguishes it from broader news/analysis siblings, though it never names an alternative.
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?
There is no explicit when-to-use or when-not-to-use guidance. An agent must infer that this is for 'why did this stock move' questions and that stock_news or combined_analysis might be better for general coverage; nothing in the text says so.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.