list_repo_groups

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

Annotations include readOnlyHint=true, and the description does not contradict this. The description adds valuable behavioral context beyond the annotation: it clarifies that the tool only lists definitions and does not verify index status, and mentions the version requirement. This is useful transparency without being verbose.

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 two sentences, directly states the core function, and immediately adds the key caveat about not checking index status. There is no fluff, and the information is front-loaded. Every phrase adds value.

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 tool with no parameters and no output schema, the description covers the essential aspects: what it lists, the version prerequisite, and the limitation regarding member repo indexing. It provides enough context for an agent to decide when to use it and what to expect. No further details are necessary.

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?

The tool has zero parameters, and the schema is empty. Per the baseline rule, 0 params yields a score of 4. The description doesn't need to explain parameters, and it doesn't try to invent any. It correctly focuses on what the tool returns and its constraints.

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 clearly states the tool lists defined repo groups, specifying it's a version-specific (v1.26+) operation. It distinguishes the purpose by explaining that each group is a named alias for indexed repos used by search_sections, which differentiates it from other list tools (e.g., list_repos) and the sibling define_repo_group.

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?

The description implies usage by explaining the tool's role in the context of search_sections and repo_group, and explicitly notes a limitation ('does not check that every member repo is still indexed'), which warns when not to rely solely on this tool. However, it doesn't name alternative tools or provide explicit when/when-not scenarios beyond the caveat.

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