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

readOnlyHint=true already tells the agent this is a safe, non-mutating read, so the bar is lower. The description adds the upstream REST endpoint for context, but omits what happens on a missing/invalid id (error vs empty) and any auth or rate-limit considerations.

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 short sentences, zero waste, with the core action front-loaded and the endpoint reference relegated to the second sentence.

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 trivial single-resource read with 100% schema coverage and readOnlyHint, the description covers what is needed to invoke it correctly. With no output schema, it could say a little more about the returned transfer object, but that is a minor gap for this tool's complexity.

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% and the single ach_transfer_id parameter is fully documented in the schema with an example format. The description only restates 'by id' and the path template, adding no meaning beyond the schema, so the baseline 3 applies.

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?

Specific verb (Retrieve) plus resource (ACH transfer) with the 'single' qualifier that implicitly separates it from the sibling increase_list_ach_transfers. It also names the exact upstream endpoint, so an agent knows precisely what operation this wraps.

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?

Usage is implied by 'by id' and 'single', which tells the agent this is the detail-fetch counterpart to the list tool, but it never states when to prefer this over increase_list_ach_transfers or what to do if the id is unknown. No explicit alternatives or prerequisites are given.

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