Trillboards DOOH Advertising

describe_endpoint

Describe a single API operation including its parameters, response shape, and error codes.

WHEN TO USE:

Inspecting an endpoint's full contract before calling it.
Discovering which error codes an endpoint can return and how to recover.

RETURNS:

operation: Full discovery record for the endpoint.
parameters: Raw OpenAPI parameter definitions.
request_body: Body schema (when applicable).
responses: Map of status code → description/schema.
linked_error_codes: Error catalog entries the endpoint can emit.

EXAMPLE: Agent: "How do I call the screen audience endpoint?" describe_endpoint({ path: "/v1/data/screens/{screenId}/audience", method: "GET" })

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "path": "<path>",
      "method": "<method>"
    },
    "name": "describe_endpoint"
  }
}

Input Schema

Name	Required	Description	Default
`path`	Yes	The operation path (OpenAPI template form, e.g. "/v1/data/screens/{screenId}/audience").
`method`	Yes	HTTP method (case-insensitive).

Schema Changelog

Changes observed during successful MCP inspections.

First observedOct 20, 2026

TDQS

A4.1/5.0

Behavior3/5

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

With no annotations provided, the description carries the full burden. It reveals the return structure and the example implies a read-only operation, but it does not explicitly state that the tool has no side effects, nor does it mention any behavior around error handling for the tool call itself (e.g., invalid path). The RETURNS section provides useful output context, but deeper behavioral disclosure is missing.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is well-structured with WHEN TO USE, RETURNS, and EXAMPLE sections. It is longer than the minimum, but each section contributes meaningful information. The example is particularly helpful without being redundant. It is not excessive, so a 4 is appropriate.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The tool is simple (2 params), has no output schema, and no annotations. The description compensates well by listing the return fields, providing usage guidance, and including an illustrative example. It covers the essential aspects needed for an agent to select and invoke the tool correctly. A small gap is the lack of explicit statement about response status codes for the tool itself, but overall it is fairly complete.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% and both parameters are described in the schema. The description adds value with a concrete example showing a real path with template syntax and method 'GET', which clarifies how to format the path. This goes beyond the schema's dry descriptions, earning a 4 rather than the baseline 3.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The first sentence clearly states 'Describe a single API operation including its parameters, response shape, and error codes.' This uses a specific verb ('describe') and resource ('API operation'), and the singular scope distinguishes it from sibling tools like list_endpoints. No ambiguity.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The 'WHEN TO USE' section explicitly lists two use cases: inspecting an endpoint's full contract before calling it, and discovering error codes and recovery. This gives clear context for when to use the tool. However, it does not explicitly mention alternatives or when not to use it, so it stops short of a 5.

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

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