perseus

perseus_validate

Read-only

Validates rendered blocks against a JSON Schema to enforce structure on configuration or task definitions. Returns pass/fail results with error messages.

Instructions

Validate a rendered block against a JSON Schema. Use to enforce structure on configuration blocks, task definitions, or any schema-constrained section. Read-only; returns pass/fail with error messages.

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": "perseus_validate"
  }
}

Input Schema

Name	Required	Description	Default
`schema`	No	JSON Schema to validate the rendered block against

Output Schema

Name	Required	Description	Default
`valid`	No	Whether validation passed
`errors`	No	Validation error messages

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv1.0.10Jun 27, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "properties": {
+    "errors": {
+      "description": "Validation error messages",
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "valid": {
+      "description": "Whether validation passed",
+      "type": "boolean"
+    }
+  },
+  "type": "object"
+}

Changed1 schema field changedv1.0.7Jun 10, 2026

changedInput schema / properties / schema / description

Previous value: -"schema= modifier for @validate"New value: +"JSON Schema to validate the rendered block against"

First observedv0.1.0May 27, 2026

TDQS

A4.1/5.0

Behavior3/5

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

The description adds that it returns pass/fail with error messages, which complements the readOnlyHint in annotations. No contradiction, but limited additional behavioral disclosure beyond what annotations provide.

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?

Two sentences, efficiently conveying purpose and return behavior. No unnecessary words.

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?

For a simple tool with one parameter and clear behavior, the description is sufficiently complete, covering purpose, usage, and return format. No missing context.

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?

The input schema covers the single parameter completely (100% coverage), so baseline 3. The description does not add extra meaning about the parameter beyond what the schema already provides.

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 validates a rendered block against a JSON Schema, with specific use cases. It is distinct from sibling tools, which have different purposes.

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 description provides clear usage context ('enforce structure on configuration blocks') and explicitly states it is read-only, but does not mention when not to use or suggest alternatives.

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