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

Annotations already declare readOnly, idempotent, non-destructive, and open-world behavior, so the safety profile is covered. The description adds the useful 'bounded' hint about result caps and tells the agent what data comes back, but says nothing about pagination semantics, rate limits, or failure modes beyond what the schema's cursor/limit fields imply.

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?

Two sentences, zero filler, with the resource and returned-fields summary front-loaded ahead of the use-case sentence. Nothing is wasted and nothing is buried.

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 usefully enumerates the returned fields (codes, contacts, state, tax status, balances, timestamps), which is exactly the missing context. Minor gaps remain around result ordering and pagination behavior, but the core call guidance is present given the schema's cursor documentation.

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 83%, so the schema already documents limit, cursor, begin_time, end_time, and _apiKey. The description only indirectly touches parameters ('bounded' → limit, 'recently created' → begin_time/end_time) without adding format or interaction detail, so 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 ('Return bounded Recurly customer accounts') and enumerates the fields returned (codes, contact details, state, tax status, balances, timestamps), which makes it unambiguous versus siblings like recurly_list_invoices or recurly_list_subscriptions. It stops short of explicitly naming those siblings as alternatives, so it lands at 4 rather than 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?

'Answers which billing accounts are active, inactive, or recently created' implies the query intents this tool serves, which is useful. However there are no explicit when-to-use/when-not conditions and no reference to alternative tools (e.g., a customer-search tool) for narrower lookups.

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