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

Adds substantial behavior beyond the annotations: partial-update semantics, the billing consequence of raising metered channels (pay-per-use at the pool's metered rate, in USD), the two-call preview/confirmation_token gate, immediate application for all other changes, and token-retry idempotency ('a repeat returns the original result'). This is exactly the kind of context annotations (destructive/idempotent hints) cannot convey.

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?

Purpose and scope are front-loaded in the first two sentences, and the confirmation-gating rule follows logically. The prose is dense and mostly earns its length, though the billing explanation could be tightened slightly.

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 correctly states the return ('the updated group, or a readable error'), and it covers the confirmation flow, partial-update behavior, and billing implications. An agent has everything needed to invoke this correctly, including the non-obvious two-call path.

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 the baseline is 3; the description goes further by explaining why confirmation_token exists (billing-gated metered increase) and clarifying that raising shared_channels_count is an allocation, not a purchase. That rationale is not present in the schema, though the field-level mechanics largely are.

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 (reconfigure/update) and a specific resource (Shared Capacity Group), and enumerates exactly which fields can change (name, shared_channels_count, metered_channels_count). An agent can immediately distinguish it from create_capacity_group, delete_capacity_group, and list_capacity_groups 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?

Gives clear context on when the tool is appropriate, including partial-update semantics ('Only the provided fields are changed') and the precise condition that triggers the two-call confirmation flow (raising metered_channels_count). It does not explicitly name sibling alternatives (e.g., buy_capacity_channels for actually purchasing channels), so it stops short of a 5.

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