Run custom stock screens against Yahoo Finance's public screener JSON to filter and sort equities by chosen criteria.
Yahoo Finance custom screener. Runs a constrained Yahoo Finance custom screener query using Yahoo's public screener JSON shape.
| Name | Required | Description | Default |
|---|---|---|---|
| request | Yes | Custom screener request |
Changes observed during successful MCP inspections.
v1.17.5Input schema / properties / request / propertiesAdded value: +{
+ "count": {
+ "type": "integer"
+ },
+ "offset": {
+ "type": "integer"
+ },
+ "query": {
+ "additionalProperties": {},
+ "type": "object"
+ },
+ "quote_type": {
+ "type": "string"
+ },
+ "sort_asc": {
+ "type": "boolean"
+ },
+ "sort_field": {
+ "type": "string"
+ }
+}Input schema / properties / request / requiredAdded value: +[
+ "query"
+]v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description must carry the full burden of behavioral disclosure. It doesn't mention read-only status, authentication needs, rate limits, response format, or any side effects. It only says it 'runs a query', leaving the agent blind to safety and operational characteristics.
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 description is a single sentence, so it is concise, but it doesn't front-load useful information. It's vague and doesn't earn its place with actionable details; brevity without substance is not effective.
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 tool with a nested object parameter and a free-form query, this description is severely incomplete. No output schema, no explanation of query syntax, no constraints on allowed fields or operators, and no examples. An agent has almost no chance of calling 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?
The only parameter is 'request' with a generic schema description 'Custom screener request'. The tool description adds nothing about the required structure (e.g., the query object, count, sort fields). With low schema coverage (no field-level descriptions), the description fails to compensate, leaving the agent unable to construct a valid request.
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 verb ('runs'), resource ('Yahoo Finance custom screener'), and notes it is a 'constrained' query, implying some differentiation from the regular screener. However, it doesn't explicitly distinguish from the sibling yahoo_finance_screener, so it lacks a clear point of contrast.
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 the standard yahoo_finance_screener or other finance tools. The word 'constrained' hints at a limited scope but doesn't explain when the custom variant is preferred or what constraints apply.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.