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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. Beyond that the description adds almost nothing: no indication of whether the result is a list, whether it includes addresses or geocodes, or how large a network may be returned. The '(Source: NCUA.)' note gives provenance only.

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 with the resource statement front-loaded and zero filler. The parenthetical source citation is borderline but does provide useful provenance for the underlying data.

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 single-parameter lookup with no output schema, the description is minimally sufficient — the agent knows what it retrieves and what key it needs. However, with no output schema the description should at least sketch the return shape (list of ATM locations, fields, ordering), which it omits entirely.

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% and the single parameter is documented as an NCUA charter number with an example, so the schema does the work. The description neither restates nor extends parameter meaning, which is acceptable at this coverage level but adds no value.

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 resource ('ATM network') scoped to a single credit union, which is clearly distinct from a branches or general profile lookup. It stops short of naming the nearest sibling (cu_branches) or otherwise contrasting the two, so an agent must infer the boundary.

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?

There is no explicit when-to-use guidance, no prerequisites, and no mention of alternatives such as cu_branches for physical branch locations. The only implied usage comes from the required cu_number parameter, which the agent must read from the schema rather than the description.

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