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

Annotations already declare readOnlyHint=true, so the safety profile is covered by structured data. The description adds useful context that members can be pulled in via fields=["people"], but says nothing about the shape of the response or whether unfound ids error out. With annotations carrying the safety burden, a 3 is appropriate.

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?

Two short sentences with the core operation front-loaded and the optional-fields hint immediately after. No padding or redundant restatement of the tool name.

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 read-only single-resource fetch with full schema coverage and readOnlyHint set, the description is nearly sufficient. The only gap is that there is no output schema, so a one-line hint about the returned group shape would close the loop, though the low complexity makes this minor.

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%, so both parameters are already documented in the schema, making 3 the baseline. The description's note that fields=["people"] returns members largely restates the schema's 'people (members and their position)' entry, adding little new meaning.

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 ('Fetch one group by id') and the singular scope distinguishes it implicitly from the list_groups sibling. It does not name an alternative tool explicitly, but an agent can identify the operation 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 only implied: use it when you need a single group rather than a list. There is no explicit when-to-use guidance, no mention of prerequisites such as needing a valid group id, and no exclusion rules pointing at sibling tools.

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