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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds a useful behavioral signal that engagement ('what they did with them') is included in the result, but it says nothing about pagination, result ordering, or empty-history behavior beyond what the schema's start/limit fields imply.

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 front-loaded sentence with no filler; the scope and content are stated immediately. It is terse to the point of being a fragment, which limits how much structure it can offer.

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 retrieval tool with full schema coverage and no output schema, the description covers what is fetched. However, it does not describe the shape of the returned history (paginated list of send/engagement records), which matters since there is no output schema to fall back on.

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 all three parameters (member_id, limit, start) are already documented in the schema, including the next_start pagination hint. The description adds no parameter-level meaning beyond what the schema provides, so 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 resource and scope: the mailing history of one member, including sent mailings and engagement ('what they did with them'). It implicitly distinguishes itself from siblings like emma_list_mailing_activity and emma_get_member by being per-member mailing history, but never names those siblings explicitly.

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 statement of when to use this versus emma_get_member, emma_list_mailing_activity, or emma_list_mailings. Usage is only inferable from the phrase 'one member' and the required member_id in the schema.

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