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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive). The description adds real value beyond them: pagination behavior, scoping to the authenticated customer, and semantics of key fields like metered_rate variability and USD-only amounts. No rate limits or auth details, so not a 5.

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?

Front-loads the core purpose and then enumerates return fields in a single dense paragraph. The parenthetical asides (metered-rate orders of magnitude, DID country coverage) earn their place, but the run-on structure is heavy and would scan better split into shorter sentences.

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 carries the full burden of describing return values and does so comprehensively: id, name, channel counts, pricing, currency, dates, covered_country_isos, and pagination meta. Nothing an agent needs to call or interpret this tool 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 and page_size are fully documented in the schema and the description adds no syntax beyond 'Results are paginated.' Baseline 3 is appropriate when the schema carries the parameters.

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 (List) and resource (Capacity Pools), then defines the domain concept and what a pool contains, distinguishing it from the sibling list_capacity_groups. An agent knows exactly what this returns and how it differs from adjacent tools.

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?

Embeds actionable usage context: check covered_country_isos before creating a group for a country, and weigh metered_rate alongside monthly_price when choosing a pool. This is clear guidance, though it never explicitly names an alternative sibling or an exclusion condition.

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