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

The annotations declare readOnlyHint=true, so the tool is known to be safe. The description adds that the response is identical to the MCP resource of the same name and that it should be used only once, offering behavioral context beyond the annotation.

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 three sentences long, front-loaded with the core purpose. Every sentence adds value: definition, prerequisite/usage context, and response/usage caveats.

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?

Given the tool's simplicity and read-only annotation, the description covers its purpose, prerequisites, usage conditions, and relationship to the resource. The statement about the response being identical to the resource compensates for the absent output schema.

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 tool has no parameters, so the empty schema is entirely complete (100% coverage). The description adds no parameter details because none are needed, aligning with the baseline for zero-parameter tools.

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 states precisely that the tool provides 'the unit tests (code examples) for HMR', and differentiates itself from the sibling tools by specifying that it contains code examples demonstrating best practices. This clearly identifies the resource being accessed.

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?

It explicitly instructs to always call `learn-hmr-basics` and `view-hmr-core-sources` first, and states when to use this tool: 'when you need to write some code using the HMR library'. It also advises to use it only once and prefer it over the equivalent resource, providing clear selection guidance.

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