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

With readOnlyHint=true and destructiveHint=false already supplied, the description correctly adds cost context ('Repeated requests may purchase data again'), which annotations do not cover. But that cost information is self-contradictory — 'at least 10 Nexscope credits' in one sentence and '1 credit per request' a few lines later — which leaves an agent unable to predict the price of a call.

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 core sentence is good and front-loaded, but the remainder is padded with supplier boilerplate that repeats the same instructions twice ('Pass username, handle, or url', 'GitHub User API View Pricing', 'Actual supplier units are reported per request') and includes conflicting credit figures.

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 two-parameter read-only lookup with no output schema, the description usefully lists what fields are returned, which is valuable. It falls short on cost clarity (contradictory figures) and on placing the tool within the large family of GitHub user sub-resources, which is the main ambiguity an agent faces here.

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%, so both url and handle are already documented in the schema. The description restates the same accepted forms (username, handle, full URL) without adding anything, such as what happens if both are supplied or which wins when they conflict.

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 opens with a specific verb+resource ('Retrieves public GitHub user details') and enumerates the returned fields (bio, company, follower counts, repo counts, timestamps). It does not, however, distinguish this from the many GitHub siblings (social_github_user_followers, social_github_user_repositories, social_github_user_activity, etc.), so an agent cannot tell from the text alone which one to pick for a given need.

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?

There is no when-to-use or when-not-to-use guidance and no mention of alternative tools. The repeated instruction 'Pass username, handle, or a full GitHub user url' is input formatting guidance, not selection guidance, and it does not address the sibling tools that cover followers, repos, contributions or activity.

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