Fiji MCP Server

Overview Schema Source Related Servers Discussions Admin

describe_plugin

Read-onlyIdempotent

Resolves a Fiji command by name and returns its SciJava input metadata. For legacy plugins without metadata, use run_macro instead.

Instructions

Resolve one command by name and return SciJava input metadata when available. Legacy ImageJ1-only plugins may omit inputs; use run_macro in that case.

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": {
      "command_name": "<command_name>"
    },
    "name": "describe_plugin"
  }
}

Input Schema

Name	Required	Description	Default
`command_name`	Yes	Command or plugin title as shown in Fiji (exact or partial match).

Output Schema

Name	Required	Description
`ok`	No
`command`	Yes	Matched command record.
`inputs`	Yes	Declared inputs when CommandService exposes them.
`inputs_available`	Yes	True if any input metadata was returned.
`note`	Yes	Guidance when metadata is incomplete (legacy plugins).

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.3May 27, 2026

TDQS

A4.5/5.0

Behavior4/5

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

Annotations already declare the tool as read-only and idempotent. The description adds context that metadata is returned only when available and that legacy plugins may lack inputs, providing further behavioral insight 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.

Conciseness5/5

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

The description is two sentences with no filler. The first sentence states the core purpose, the second adds critical usage guidance. Every part earns its place, making it highly efficient.

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

Completeness5/5

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

With one fully documented parameter, existing annotations, and an output schema (implied by 'has output schema'), the description covers the essential context: what it does, when to avoid it, and what it returns. No gaps remain.

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 coverage is 100%, so the parameter command_name is already well-documented. The description only minimally adds meaning by implying the command is resolved by name, which overlaps with the schema description. Baseline score of 3 is appropriate.

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 resolves a command by name and returns SciJava input metadata, which is a specific verb+resource. It also distinguishes from the sibling tool run_macro for legacy plugins, making the purpose unambiguous.

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

Usage Guidelines5/5

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

The description explicitly advises to use run_macro instead for legacy ImageJ1-only plugins that may omit inputs, providing clear when-to-use and when-not-to-use guidance relative to an alternative tool.

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