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

Annotations only cover readOnlyHint and openWorldHint, and the description adds substantially more: no authentication required, a first-lookup latency of ~25 seconds, a 'pending' status with retry_after_s to poll, and the visibility limit that runtime-only exports without type declarations are not found.

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 definition is dense but front-loaded: what it checks, then what it returns, then latency/retry behavior, then limits and usage. Every sentence carries information, though the single long first sentence is heavy to parse.

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?

With no output schema, the description carries the return-value burden and does so fully (found flag, kind, signature, import module path, deprecation plus message, close-name suggestions), and it also covers latency, async retry, and applicability limits for a 4-parameter tool.

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?

Schema description coverage is 100%, with each parameter (name, module, symbol, version) already documented including examples and version-resolution rules. The description adds no parameter-level syntax or constraint beyond that, so the baseline 3 applies.

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?

States a specific verb and resource ('Checks whether an exported function, class, type or constant ... exists in a specific version of an npm package') and names the mechanism (TypeScript declarations). It is clearly distinguishable from siblings like find_compatible_version or version_status.

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?

Gives an explicit trigger ('Use it before writing code that calls a library API you are not sure exists ... especially after a major upgrade') and routes to the alternative for a different need ('For a complete list of what changed between two versions use upgrade_impact'). Scope limits are also stated, so the agent knows when this tool will not help.

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