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

Annotations already establish the safety profile (readOnly, idempotent, non-destructive, open-world), and the description adds genuinely new behavior: billing model (1 credit per successful lookup, implying failures are free), the 404 semantics for unindexed usernames, and the auth requirement (own API key, no platform key). It does not cover rate limits or latency, but the added context is substantive.

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-loads purpose, then payload contents, then cost/auth/404 caveats, then an example — a sensible ordering. The long parenthetical list of return fields is dense but each item is informative; only minor trimming is possible.

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 the burden of explaining what comes back, and it does so via the work-pattern/collaboration/professionalism breakdown. Cost, failure mode, and auth are all covered, leaving it near-complete for a two-parameter lookup tool.

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% — both github_username and _apiKey are documented in the schema, including the x-api-key header detail. The description only restates the key requirement and supplies a concrete example invocation, adding little beyond the structured fields, so the baseline of 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 behavioural intelligence for one developer by GitHub username' — and enumerates what the return payload contains (work pattern, collaboration style, professionalism signals, recency). The scope ('one developer', 'by GitHub username') distinguishes it from the search/list siblings, but it never explicitly contrasts itself with revternal_enrich_developer, which an agent could reasonably confuse it with.

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?

Provides real operational context: single-developer lookup, flat 1 credit per successful call, 404 when the username is not yet indexed, and BYOK requirement. However, it never states when to prefer this over revternal_enrich_developer, revternal_enrich_person, or the search tools — the choice is left to inference.

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