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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered without the description. The description adds only the subscribed/unsubscribed scoping option and says nothing about pagination defaults, result caps, or ordering behavior, so it adds limited behavioral context beyond annotations.

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 or repetition. It is efficient, though the terseness borders on under-specification given the tool's 10 parameters.

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?

With 10 parameters, structured filters, free-text search, sorting, pagination, and engagement filtering, plus no output schema, the description covers only the subscribed toggle and omits the filtering/pagination model entirely. The rich schema compensates substantially, but an agent reading the description alone would underestimate the tool's capabilities.

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 90%, so the schema already documents id, page, sort, limit, match, order, search, filters, and engagement in detail. The description only echoes the 'subscribed' boolean, adding no syntax or semantics beyond the schema, which is the expected baseline when the schema does the heavy lifting.

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 ('List subscribers of an audience'), which is unambiguous against single-record siblings like get-audience-subscriber. It does not explicitly name or differentiate from list-contacts or the bulk-* audience-subscriber siblings, so it stops short of a 5.

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 guidance on when to use this versus alternatives (e.g. list-contacts, get-audience-subscriber, bulk-remove-audience-subscribers). The clause 'optionally only subscribed or unsubscribed' describes a parameter option rather than tool-selection context, leaving usage to inference.

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