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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is covered. The description adds meaningful context by enumerating the specific analysis dimensions (minified+gzipped size, tree-shakeability, dependencies, ESM/CJS), which informs the agent about the tool's output focus. It does not describe error behavior or return format, but that is acceptable given the output schema exists.

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 a single, information-dense sentence: 'Bundle size analysis — minified + gzipped, tree-shakeability, dependencies, esm/cjs detection.' Every element adds value, and the dash after the main phrase highlights the key features. There is zero redundancy or filler.

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?

For a simple lookup tool with three well-documented parameters, strong annotations, and an output schema, the description provides sufficient context. It identifies the core purpose and key output dimensions, and the schema and annotations cover parameters and safety. No critical information for agent invocation is missing.

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?

Input schema coverage is 100%, with clear descriptions for each parameter (package, version, record). The description adds no parameter-specific guidance beyond what the schema already provides. Since the schema fully documents parameters, a baseline of 3 is appropriate.

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: bundle size analysis, listing specific metrics (minified + gzipped, tree-shakeability, dependencies, ESM/CJS detection). This distinguishes it from sibling tools like scan_dependency, which focuses on dependencies but not bundle size. The verb 'analysis' is implied and the resource is the npm package.

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 gives no guidance on when to use this tool versus alternatives. It does not mention any exclusions, prerequisites, or scenarios where another tool might be more appropriate (e.g., 'Use scan_dependency for dependency vulnerabilities'). The usage context must be inferred solely from the tool name and description.

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