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

With no annotations, the description must carry behavioral disclosure. It states 'The body is discarded,' which is a useful behavioral trait (no persistence). However, it does not disclose return values, error handling, network activity, or side effects. The tool might accept multiple inputs (url, json, etc.), but the description only references 'body' without clarifying which parameter that is, leaving behavioral ambiguity.

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

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

The description is extremely concise—two sentences—and front-loads the core purpose. Every word earns its place, and it avoids redundant information. It is appropriately sized for a simple validation tool, though it could optionally add a brief example or clarify parameter mapping without becoming verbose.

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

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

Despite the tool's simplicity, it has 9 parameters and no output schema. The description does not explain how these parameters are used or which one constitutes the 'body.' It does not describe the return format (e.g., boolean or error), nor does it clarify the relationship between parameters like 'url' and 'json.' This is a significant gap for an agent deciding how to invoke the tool correctly, especially with multiple possible input sources.

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

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

The schema provides 100% coverage with detailed descriptions for all 9 parameters, so the baseline is 3. The tool description adds no parameter-specific meaning beyond the schema, and it does not explain how parameters like 'json' or 'url' relate to the 'body' mentioned in the description. The schema already does the heavy lifting, so the description offers no additional semantic value.

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

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

The description clearly states the tool's function: 'Check whether a body is valid JSON.' It uses a specific verb and resource, and the name 'validate-json' reinforces the purpose. It distinguishes itself from sibling shape-check tools (domain-shape, github-repo-shape, etc.) by focusing specifically on JSON validation, leaving no ambiguity about what it does.

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

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

The description implies the use case (validate JSON) but does not explicitly mention when to use this tool versus alternatives like domain-shape or jira-key-shape. There is no guidance on when not to use it or which sibling to choose based on format. The name and description make the primary purpose obvious, but explicit routing to alternatives is absent.

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