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

Annotations already declare this a safe read (readOnlyHint=true, destructiveHint=false). The description adds substantive behavior the annotations do not cover: the estimate is percentile-basis ("80% of cases completed within N months"), the unit varies by category, authentication and plan requirements, and a legal-advice disclaimer. These are exactly the kind of extra traits that earn credit above the annotation floor.

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?

Four short sentences, front-loaded with what the tool returns before the access requirements and caveats. Every sentence earns its place; the only minor friction is the nested quoting and parenthetical, which slightly slows reading.

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?

An output schema exists, so return structure need not be explained here, and the description still usefully frames the return as a percentile figure. Auth, source and disclaimer are all covered; the only gap is guidance on how office/category affect results or when the estimate may be unavailable.

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 the baseline is 3 and the schema already documents form, office and category. The description adds only marginal parameter meaning, noting that the result unit varies by category, which hints that category changes the interpretation but not the input format.

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 (USCIS processing-time estimate for a given form) and even characterizes the shape of the returned figure. It is unambiguously distinct from siblings like get_fee and get_visa_bulletin, which retrieve different data. An agent can select it without opening the schema.

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 a real prerequisite — sign-in at a specific URL and an active plan — which is useful operational context. It does not, however, say when to prefer this tool over alternatives or when-not to call it (beyond account gating). Usage is implied rather than framed.

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