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

Annotations already declare destructiveHint=true and idempotentHint=true, so the description's job is to add detail — and it does: it discloses that the full member list is replaced wholesale, that previously published recipient links survive the replacement, and that no email is sent. That is meaningful context beyond the annotations, though it omits what happens to members lacking email addresses.

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?

Three sentences, no filler, and the core replacement behavior is front-loaded ahead of the secondary effects (link persistence, no email). Every sentence earns its place.

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 three-parameter upsert tool with a full-coverage schema, explicit annotations, and no output schema, the description covers what an agent needs: mutation scope, replacement behavior, and the non-obvious side effect that published links stay valid. Nothing material is missing.

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 id, label, and members are all documented in the schema, including the in-place update behavior on id reuse. The description only hints at the members' replacement semantics, adding little beyond what the schema already provides — baseline 3 is appropriate.

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 (save/replace a named recipient group) and immediately clarifies the upsert semantics — the supplied member list replaces the saved list. An agent can distinguish this from get_audience, delete_audience, and list_senders without opening any schema.

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 implied rather than stated: 'save or replace' tells you this is the write path for audience data, and the note about links remaining valid helps scoping decisions. However, it never names an alternative or states when NOT to use it (e.g., vs delete_audience or get_audience), so guidance is only adequate.

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