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

Goes well beyond the readOnly/idempotent annotations: 6-hour cache with data_synced_at, partial answers billed at 200, 404/503 unbilled, 429 rate limiting with retry_after_s, typical latency under 1 s (up to ~12 s on slow sources), and a prompt-injection caution about returned page text. Annotation-consistent and adds real behavioral context for billing and retry decisions.

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?

Purpose and returned facts are front-loaded before the operational details, and every clause carries information an agent needs (cost, cache, error codes, latency). It is dense and semicolon-chained, with licence/attribution boilerplate and a docs URL adding bulk, but little is genuinely wasted.

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 an output schema present, the description needn't explain return values, and it still covers cost, caching, failure modes, rate limits, latency, and trust handling. For a single-parameter read-only tool this leaves nothing material for an agent to discover by trial.

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 schema already documents owner/name forms, github.com URLs, trailing .git or /, and renamed-repo resolution. The description adds only tangential semantics ("Unknown repo 404"), which doesn't meaningfully extend the accepted input formats. 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?

Names a specific verb and resource ("Get health facts for a GitHub repository") and enumerates exactly which facts: stars, licence, activity, latest release, dependents, OpenSSF Scorecard. No sibling tool covers GitHub repository metadata (check_mcp_server and scan_agent_package target different artifacts), so an agent can select it unambiguously.

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?

Usage is implied by the enumerated facts rather than stated: nothing says when to reach for this versus, say, check_mcp_server or scan_agent_package. The description does provide operational context (free tier of 10 calls/IP/day, USD 0.003 price, caching window), which helps an agent decide whether the call is worth making, but no explicit 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.