Gemini MCP Server

Overview Schema Source Related Servers Discussions Admin

gemini_structured_output

Generate structured JSON responses from Gemini by providing a prompt and a JSON schema. Ensures output conforms to your specified format.

Instructions

Get structured JSON output from Gemini using a provided JSON schema

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": {
      "prompt": "<prompt>",
      "jsonSchema": "<jsonSchema>"
    },
    "name": "gemini_structured_output"
  }
}

Input Schema

Name	Required	Description
`model`	No	Model name (default: gemini-3.1-pro-preview)
`prompt`	Yes	The prompt to send to Gemini
`jsonSchema`	Yes	JSON schema string defining the expected output structure

Schema Changelog

Changes observed during successful MCP inspections.

First observedv2.0.0Jun 29, 2026

TDQS

B3.1/5.0

Behavior2/5

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

With no annotations, the description carries full burden but only says 'Get structured JSON output'. It does not disclose failure modes (e.g., invalid schema), response format beyond structured JSON, authentication needs, or rate limits. Minimal transparency.

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 a single sentence with no filler. It is front-loaded and efficient, though adding a brief example or usage tip could improve it without significant bloat.

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

Completeness2/5

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

No output schema is provided, so the description should explain the return value (e.g., JSON object conforming to the schema). It also lacks usage context (e.g., compare to gemini_chat for structured output). Incomplete for a tool with 3 parameters and no output schema.

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

Parameters3/5

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

Schema description coverage is 100%, so baseline is 3. The description adds no additional meaning beyond what the schema already provides (model, prompt, jsonSchema). It does not clarify expected JSON schema format or constraints.

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 description clearly states the tool's purpose: 'Get structured JSON output from Gemini using a provided JSON schema'. The verb 'get' and the specific resource 'structured JSON output' distinguish it from sibling tools like gemini_chat (free-form text) or gemini_embed (embeddings).

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

Usage Guidelines2/5

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

No guidance is provided on when to use this tool versus alternatives such as gemini_chat or when not to use it. There is no mention of prerequisites, fallback options, or comparison to sibling tools.

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