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

Annotations cover readOnly/idempotent/openWorld safety, and the description adds meaningful operational detail beyond that: free tier (first 3 calls per wallet), required header X-WALLET, no charge on upstream failure, and a 0.001 USDC x402 paywall per call. Payment/auth behavior is critical and disclosed, though rate limits or failure modes beyond billing are not described.

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?

Front-loaded purpose is good, but the description crams multiple marketing-flavored claims ('raw signal', 'ranking surface for trajectory', 'agent-to-agent dependency-selection scoring', 'autonomous agents compute momentum') that overlap and dilute the core message before getting to the essential billing details.

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 extra weight and does explain return shape (per-day download time series). Payment and auth requirements are covered. Missing only return-field specifics or failure-behavior detail.

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 coverage is 100% and only one param exists with an example provided in the schema. The description doesn't add format or semantics beyond the schema's example, so 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 (Returns) and resource (per-day download time series for an npm package) with a named data source (api.npmjs.org). It's clear, but no sibling in the list is similar enough to differentiate from, so 5 isn't earned.

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 clear context for use ('raw signal for trend and growth-rate detection', 'compute momentum/decline', 'trajectory ranking'), which tells an agent when this is the right tool. However, no explicit when-not-to-use or alternatives are named.

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