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

readOnlyHint and openWorldHint already establish that this is a safe, externally-scoped read, so the description only needs to add context. It does add the returned field categories, but says nothing about behavior when the member is not found, whether lookup by email vs id differs in errors, or rate limits.

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 naming the action, the lookup key, and the payload; nothing is redundant or padded.

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 two-parameter read tool with no output schema and full annotation coverage, the description's enumeration of returned fields is the right compensation. Only the not-found/error behavior is left unaddressed, which is a minor 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?

Schema coverage is 100% and both parameters are documented, including that list_id comes from laposta_list_lists. The description restates the id-or-email alternative without adding format or precedence semantics beyond the schema, 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 verb and resource ("Get one member of a list") plus the two accepted lookup keys and the returned field categories (state, signup/confirm dates, custom fields). It is clearly distinguishable from list-type siblings, though it does not explicitly name laposta_get_member_history or laposta_update_member as neighbors.

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... by member id or email address" implies single-record retrieval versus the listing tool, but there is no explicit when-to-use guidance, no exclusions, and no mention of when to prefer laposta_get_member_history for event data.

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