as_of

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

No annotations are provided, so the description carries the full burden. It clearly states 'Pure lookup, no ranking' and discloses the behavior of each mode, plus that every provision carries a permalink and hash. It doesn't mention edge cases like unknown documents, but that is covered in the parameter description.

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 sentences, front-loaded with the core purpose and then structured details. No filler.

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 read-only lookup with no output schema, the description covers the core behavior, modes, and a notable output feature (permalink/hash). It doesn't explicitly address error handling or pagination, but given the tool's simplicity and the rich parameter descriptions, it is sufficiently complete.

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%, but the description adds value by explaining the mode semantics and the default behavior, which goes beyond the schema's simple enum list. It also reinforces the meaning of anchors for select mode.

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?

The description opens with a specific verb+resource: 'The state of one document as it stood on one date.' This clearly distinguishes it from sibling tools like timeline or in_force_on by emphasizing a snapshot at a specific point in time. The explicit 'Pure lookup, no ranking' further separates it from search.

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?

Provides explicit guidance on when to use each mode: 'use it first on long documents' for outline, and describes select vs full. It implies this is for point-in-time lookup rather than search or diff, though it doesn't explicitly name alternative tools or exclusions.

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