Check if an npm package includes built-in TypeScript types or requires a @types/* companion package for type support.
Check TypeScript type support for a package — whether it ships built-in types (types/typings field) or has a DefinitelyTyped companion (@types/* package).
| Name | Required | Description | Default |
|---|---|---|---|
| name | Yes | Package name (e.g. 'express' or '@anthropic-ai/sdk') | |
| version | No | Semver version or dist-tag (default: 'latest') |
Changes observed during successful MCP inspections.
v0.12.2Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false, providing a strong safety profile. The description adds context about what the tool checks (built-in types vs. DefinitelyTyped) but doesn't disclose return format, error handling, or edge cases. This is comparable to the get_calls example where annotations carry the safety burden and the description adds only moderate behavioral context.
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 sentence that starts with the action verb 'Check' and immediately states the resource and scope. It avoids redundant information and is perfectly sized for the tool's simplicity.
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 read-only query tool with comprehensive annotations and full schema coverage, the description adequately covers the purpose. It doesn't explain the return shape, but that is not critical given the tool's straightforward nature and the absence of an output schema. The description is complete enough for an agent to select and invoke the tool correctly.
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 fully documents both parameters (name and version), including the default for version. With 100% schema coverage, the baseline is 3, and the description doesn't add any extra parameter semantics beyond what the schema already provides. No additional explanation of parameters is needed.
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 specifies the tool's purpose: checking TypeScript type support for a package. It distinguishes between built-in types and DefinitelyTyped companion packages, which sets it apart from sibling tools like npm_package that focus on general package info. The action verb 'Check' is specific and the resource is clearly identified.
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 when to use this tool: whenever an agent needs to determine type support for an npm package. It doesn't explicitly mention alternatives or exclusions, but given the tool's name and the explicit focus on TypeScript types, the usage context is clear. A direct comparison with npm_package or npm_health would have improved the score.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.