NPM Sentinel MCP

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

Annotations provide readOnlyHint=true, openWorldHint=true, and idempotentHint=true, indicating safe, non-destructive, and repeatable behavior. The description adds value by specifying the check is for 'TypeScript types availability and version', which clarifies the scope beyond what annotations convey. However, it lacks details on rate limits, error handling, or output format, leaving some behavioral aspects unclear.

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, clear sentence that directly states the tool's purpose without any unnecessary words. It is front-loaded and efficiently communicates the core functionality, making it easy for an agent to quickly understand what the tool does.

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 moderate complexity (checking TypeScript types), annotations cover safety and idempotency, but there is no output schema to clarify return values. The description specifies the check includes 'availability and version', which helps, but it does not detail the output structure or potential edge cases (e.g., handling packages without types), leaving some contextual gaps.

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 input schema has 100% description coverage, with the 'packages' parameter clearly documented as 'List of package names to check types for'. The description adds no additional semantic information about parameters beyond what the schema provides, such as format examples or constraints, so it meets the baseline for high schema coverage.

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 action ('Check') and the resource ('TypeScript types availability and version for a package'), making the purpose understandable. However, it does not explicitly differentiate this tool from its many siblings (e.g., npmVersions, npmDeps, npmQuality), which focus on different aspects of npm packages, so it falls short of a perfect score.

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 provides no guidance on when to use this tool versus alternatives. With 18 sibling tools available, including npmVersions and npmDeps, the agent is left to infer usage based on the tool name alone, which is insufficient for effective tool selection.

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