fanduel_racing_call

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint, covering safety. The description adds valuable context: the query text lives server-side, boilerplate variables default automatically, auth is not needed, and returns a JSON object. It also states that guessing an operation returns an error (in schema description), which adds operational transparency beyond the annotations.

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?

At four short sentences plus Returns/Auth lines, the description is compact and front-loaded. The first sentence immediately states the purpose, and every subsequent sentence adds information about operation discovery, defaults, return type, and auth.

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?

The tool is a generic GraphQL caller with no output schema, but the description covers the key needs: how to discover operations, that variables are optional with defaults, that auth is not required, and the return format. It could be more explicit about error behavior or response structure, but the pointer to the operations resource and the schema's param descriptions fill most gaps.

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 schema descriptions are thorough (100% coverage): the operation parameter specifies valid names come from the catalogue resource and warns about errors, and the variables parameter explains that required keys depend on the operation. The description adds 'the boilerplate variables (brand/product/device/profile) default automatically, so most calls need no variables,' which helps the agent decide when to pass variables.

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 clearly states the tool's action: 'Call any FanDuel Racing (TVG) GraphQL operation by name + variables against api.racing.fanduel.com/cosmo/v1/graphql.' It specifies the verb (call), resource (FanDuel Racing GraphQL API), and scope (any operation), distinguishing it from sibling tools like fanduel_racing_messages or fanduel_sb_call.

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 instructs the agent to 'Read fanduel://racing/operations for the operation list + variable signatures,' providing a clear next step for using the tool. It also explains that most calls need no variables due to automatic defaults, helping the agent decide when to omit variables. However, it does not explicitly state when to prefer dedicated FanDuel racing tools over this generic caller, so it lacks explicit exclusion guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.