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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description still adds two things not in the annotations: the scope of returned data ('public data') and a credit cost of 1 per request. It does not mention the 10-result cap or pagination behavior, which are left entirely to the schema.

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?

Three short sentences, each carrying distinct information: purpose, safety/scope, and cost. Purpose is front-loaded and there is no filler or restatement of the title alone.

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 three-parameter read tool with full schema coverage and no output schema, the description covers purpose, read-only nature, data scope and credit cost. The remaining gap is return-shape expectation (a list of repos with a nextCursor), which the cursor parameter implicitly signals in the schema.

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 explains count (1-10, default 10), cursor (previous response's nextCursor) and username (login or profile URL). The description adds no parameter-level meaning beyond that, 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?

States a specific verb and resource ('List the repositories a GitHub user has starred'), which is precise enough to separate it from github_search_repositories and github_list_repositories. It stops short of explicitly contrasting with the sibling list of a user's own repositories, so an agent must infer the distinction from the word 'starred'.

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 narrow scope: fetch the repos a user has starred, given a username. There is no explicit statement about when to prefer github_list_repositories or github_search_repositories instead, and no prerequisites mentioned. An agent can figure it out from the name, but the description does no routing work.

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