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

Annotations already cover readOnlyHint/openWorldHint/destructiveHint, so the safety profile is set. The description adds genuinely useful behavior beyond that: the meaning of 'balance' (amount owed on open invoices), the pagination contract (pass next_cursor back as cursor), and the auth requirement (Cotlet API key with app access).

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-loaded with the resource and returned fields, then scope, search, balance definition, pagination, and auth. Every sentence carries information, though it is slightly list-like rather than tightly prioritized.

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?

For a filtered list tool with no output schema, it covers returned fields, filtering scope for type, search semantics, pagination, and auth. It stops short of describing default limit or ordering behavior, but is otherwise complete enough to invoke correctly.

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 coverage is 100%, so the baseline is 3. The description adds meaning beyond the schema: it defines what balance represents, restates the search match fields, and explains cursor as the value returned from a prior call, which is valuable given the absence of an output schema.

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 (lists) and resource (customers) and clarifies the entity scope by naming the returned fields (address, email, phone, balance) and the supported types (customers, prospects, or both). The 'List' verb distinguishes it cleanly from the sibling yardbook_get_customer and yardbook_create_customer.

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?

It indicates the tool lists customers/prospects and that search matches four fields, which implies retrieval usage. However, it never states when to use this over yardbook_get_customer or a search-focused alternative, and gives no exclusions or prerequisites beyond the API key note.

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