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

Annotations already declare readOnlyHint and openWorldHint. Beyond that, the description adds valuable context: the tool is deterministic with no LLM, it costs $0.003 USDC on Base via x402, and payment must be passed in _meta['x402/payment']. It also includes an example output shape.

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 front-loaded with purpose, followed by return fields, an example, and pricing. The example JSON is somewhat long but useful for understanding the output, and every section contributes relevant information.

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?

There is no output schema, so the description compensates by listing return fields and providing an example output object. It also covers the non-obvious payment requirement and confirms the operation is deterministic and read-only.

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% for the single 'repo' parameter, which is documented as 'owner/name'. The description does not add new parameter constraints, but the example output shows the expected repo format as 'coinbase/x402', reinforcing the schema.

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 gives a specific verb and resource: 'GitHub repo stats and latest release', then enumerates the snapshot fields. It does not explicitly contrast with sibling tools, but none of the listed siblings overlap, so the purpose is still clear.

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 describes what the tool returns but gives no explicit when-to-use, when-not-to-use, or alternative guidance. An agent can infer that this is for fetching GitHub repository metadata, but no routing guidance is provided.

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