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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower; the description adds useful behavior beyond them by disclosing that results are paginated and enumerating the returned fields (id, name, channel counts, assigned DIDs, pool id/name, pagination meta). It stops short of stating default page size or rate limits, which the schema covers for defaults.

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?

Effectively two sentences, front-loaded with the resource and scope, then the return contents. Dense but every clause (filter, pagination, returned fields) carries information; minor density is the only cost.

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 no output schema, the description compensates by enumerating the return payload and noting pagination, and it acknowledges the optional filter for the one non-pagination parameter. Nothing an agent needs to call this list tool correctly 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 page, page_size, and capacity_pool_id are already documented with defaults and bounds in the schema. The description only echoes the capacity_pool_id filter concept without adding syntax or format detail beyond it, which matches the baseline-3 case 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 the authenticated customer's Shared Capacity Groups') and disambiguates the resource from the similarly named list_capacity_pools by clarifying these are capacity groups, each tied to a Capacity Pool. An agent can distinguish this from the pool-listing sibling without opening either 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 by 'optionally filtered by Capacity Pool,' which tells the agent the filter exists but not when to prefer this tool over list_capacity_pools or other list_* tools. No explicit when-to-use, prerequisites, or exclusions are given, 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.