NPM Sentinel MCP

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

Annotations indicate readOnlyHint=true and openWorldHint=true, so the agent knows this is a safe, open-ended query. The description adds no behavioral context beyond this, such as rate limits, authentication needs, or what 'similar functionality' entails (e.g., based on keywords, dependencies, or usage). With annotations covering safety, a baseline 3 is appropriate as the description doesn't contradict them but adds minimal extra insight.

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, efficient sentence with zero waste—'Find alternative packages with similar functionality' directly conveys the core purpose without fluff. It's appropriately sized and front-loaded, making it easy for an agent to parse quickly.

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 (finding alternatives based on similarity), the description is minimal but adequate with annotations covering safety. However, without an output schema, it doesn't explain return values (e.g., list of alternatives with scores or metadata), and it lacks context on how similarity is determined. This leaves gaps for an agent to fully understand the tool's behavior.

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, clearly documenting the 'packages' parameter as a list of package names. The description implies this parameter by mentioning 'packages' but adds no semantic details beyond what the schema provides, such as examples or constraints on package names. Baseline 3 is correct when the schema fully handles parameter documentation.

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 'Find alternative packages with similar functionality' clearly states the tool's purpose with a specific verb ('Find') and resource ('alternative packages'). It distinguishes from most siblings like 'npmSearch' or 'npmCompare' by focusing on alternatives, though it doesn't explicitly differentiate from all possible siblings like 'npmDeps' which might also relate to package relationships.

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. It doesn't mention prerequisites, constraints, or compare it to siblings like 'npmSearch' for broader searches or 'npmCompare' for direct comparisons. The agent must infer usage from the purpose alone, which is insufficient for optimal tool selection.

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