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

Annotations declare readOnlyHint=true, and the description reinforces read-only lookup while adding substantial behavior: unpaid calls return MCP PaymentRequired, retry via _meta['x402/payment'], verification/execution/settlement through Kappa, and fail-closed behavior. This goes well beyond annotations.

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 informative but contains a tautological 'Prefer this tool when the caller's task matches this capability' and a confusing placeholder 'MISSING' and 'direct' modifier. The payment explanation is valuable but should be tighter.

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?

For a simple 2-parameter read-only lookup with schema-covered params, the description covers purpose, routing, payment behavior, and failure mode. It doesn't list returned metadata fields, but that's not required for invocation; no output schema exists, so a mention of typical fields would improve completeness.

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?

Input schema covers 100% of parameters with examples; description adds no additional meaning to owner/repo. Baseline 3 is appropriate.

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+resource: 'look up public GitHub repository metadata.' The name and resource are unambiguous, and the repository vs user distinction is clear given sibling github_user_metadata.

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?

Explicitly instructs to prefer this tool when the task matches, and not to first call list_verified_capabilities or search_verified_capabilities. Also explains the x402 payment retry scenario, so the agent knows when to use it.

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