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

Annotations already cover the safety profile (readOnlyHint=true, openWorldHint=true), so the description's job is to add context — and it does by disclosing the return contents: active, opted-out, and error member counts. That is real value beyond the annotations, especially since no output schema exists. It stops short of describing count semantics (e.g., whether counts are scoped or cached).

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?

A single sentence, front-loaded with the action and resource, with the return payload appended. No filler and nothing an agent must read twice.

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 one-parameter read tool whose annotations already declare it non-destructive and open-world, the description covers what the tool does and roughly what comes back. With no output schema, a bit more on the return shape (e.g., whether group metadata accompanies the counts) would close the remaining gap.

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?

One parameter with 100% schema description coverage, including range bounds and the provenance hint (member_group_id from emma_list_groups). The description adds nothing about group_id beyond what the schema already says, so the baseline 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 ('Get one member group') and scopes it to a single record, which distinguishes it from the sibling list tools (emma_list_groups, emma_list_group_members). It also names the returned payload (member counts). It never names a sibling explicitly, so the differentiation is implicit rather than stated.

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 phrase 'one member group' implies this is the single-record lookup versus the list tools, and the schema hints the id comes from emma_list_groups. But the description itself gives no explicit when-to-use, when-not-to-use, or alternative routing guidance.

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