YC GraphQL MCP

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yc_introspect_schema

Read-onlyIdempotent

Read the full GraphQL schema without descriptions to inspect available types and fields, capped at 2 MB so large schemas require targeted type inspection.

Instructions

Read the full GraphQL schema without descriptions. Limited to 2 MB; prefer targeted type inspection for large schemas.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "yc_introspect_schema"
  }
}

Input Schema

Name	Required	Description	Default
No arguments

Output Schema

Name	Required	Description	Default
`ok`	Yes
`data`	No
`error`	No
`untrustedContent`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv2.1.0Nov 12, 2026

TDQS

A4.1/5.0

Behavior4/5

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

The annotations already establish that this is a safe, read-only, idempotent read, so the description's job is to add useful behavioral details. It does: the result set omits descriptions, and output is capped at 2 MB. What remains unclear is whether exceeding the cap produces truncation or an error.

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

Conciseness5/5

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

It is two tight sentences that front-load the core behavior and then give the escape hatch condition. No sentence is wasted, and no information is buried.

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 description covers all three things an agent needs to know: what the tool returns, whether descriptions are included, and the size limit, while an output schema handles return structure. The only gap is the outcome of exceeding 2 MB, which affects whether the agent should attempt the call on a very large schema.

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?

The tool takes zero parameters, so there is nothing to disambiguate and the baseline of 4 applies. The description adds no parameter-level noise, which is appropriate.

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

Purpose4/5

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

The description gives a specific verb and resource: reading the full GraphQL schema and deliberately leaving out descriptions. The phrase 'without descriptions' also hints at how this tool differs from the schema-describing sibling, but the description does not name that sibling or any other, so the boundary is only implied.

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?

It states a clear usage rule: 'prefer targeted type inspection for large schemas.' This tells the agent when not to use the tool and points to an alternative pattern, but because that alternative is described generically rather than by name, the agent must infer that it is yc_describe_type or a related tool.

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