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

Annotations already declare readOnly, idempotent, non-destructive, and openWorld. Beyond those, the description adds genuinely useful context: the $0.002/call pricing with 10 free/day and x402 payment options on overage, plus error behavior (isError with a message, not charged on failure). This is substantive operational detail the annotations do not provide.

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 front-loaded with the returned fields and the health-judgment purpose, then layers in pricing and error semantics. The long field enumeration is dense but informative and earns its place. Minor redundancy in the trailing pricing/error sentences keeps it from a 5.

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?

An output schema exists, so return-value explanation is rightly omitted. With rich annotations, a single fully-documented parameter, and added coverage of pricing, activity semantics, and error behavior, the description is nearly complete. Only the lack of alternative-tool routing leaves a small gap.

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% and the single 'repo' parameter is fully documented in the schema ('owner/name or a github.com URL'). The description adds no additional parameter syntax beyond noting data comes 'From the GitHub REST API.' This is the baseline 3 when the schema does the heavy lifting.

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 names the specific resource (a GitHub repository) and enumerates exactly what it returns (stars, forks, open issues, last commit, latest release, license, languages, contributors, archived), plus the underlying goal ('is it alive and trustworthy?'). An agent immediately understands the scope without opening any schema.

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?

It gives clear usage context: the 'activity' field 'summarizes days since last push and last release so an agent can judge whether a project is maintained.' This tells the agent when the tool is appropriate (assessing project health). However, it names no alternative tool or exclusions, so it stops short of full when/when-not guidance.

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