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

Annotations already assert readOnlyHint=true, and the description reinforces this with 'read-only observability; this server does NOT create transfers' — useful confirmation in a family that also contains create/mutate tools. It also exposes the HTTP method and path, adding an observable trait beyond the structured fields, though it says nothing about rate limits or result volume.

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?

Three tight clauses with zero filler: purpose and read-only scope first, then endpoint, then filtering. Every sentence carries information an agent can act on.

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?

No output schema exists, so the description arguably should hint at the returned transfer shape and pagination model, yet it only mentions the cursor indirectly via the schema. For a 4-parameter read-only list tool whose parameters are fully documented, this is adequate but leaves return-value expectations to the API reference.

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 all four parameters (limit, cursor, status, account_id) are already documented in the schema. The description's 'Filter by account and status (sent as status.in)' restates what the status parameter already says, adding no new syntax or semantics — the baseline 3 for schema-covered 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 and resource ('List ACH transfers') and pins the underlying endpoint (Increase API: GET /ach_transfers). The resource is distinguishable from sibling list tools such as increase_list_wire_transfers and increase_list_check_transfers, though no sibling is named explicitly.

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?

The description gives filtering context ('Filter by account and status') and a strong negative signal ('this server does NOT create transfers'), which implicitly steers creation intent elsewhere. However, it never states when to prefer this list tool over increase_get_ach_transfer for a single record, leaving that routing to inference.

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