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

Annotations already cover read-only, idempotent, non-destructive, closed-world, so the safety profile is settled. The description still earns credit for disclosing non-obvious mechanics: applicability scopes are drawn from 'any scope the record holds' (e.g. 'cases commenced on or after'), and changes between periods are returned by default while full period texts require include_period_texts. That is real behavioral content not present in the annotations.

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?

It is a single sentence with no filler, which is good, but the sentence is hard to parse on first read: the relative clause 'which later changes to a provision reach it' delays the actual payload. Leading with the precondition rather than the outcome makes it less front-loaded than it could be.

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 shape need not be described, and the description covers the two things an agent could not infer: that scope resolution is broad ('any scope the record holds') and that period text is opt-in. Remaining ambiguity is minor — what happens for a commencement date before any recorded scope, or whether path must resolve to an existing provision.

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%, so the schema already documents path, commenced, date, and include_period_texts, which sets the baseline at 3. The description reinforces the meaning of 'commenced' by tying it to the case commencement date and to the retrospective scope rules, but it says nothing about include_period_texts or the 'today' default for date, so it does not exceed the schema.

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 identifies a specific computation on a specific resource: given a commencement date and a provision file, it returns which later amendments reach that case and the text that applies. That is materially distinct from the sibling tools it sits beside (provision_history, changes_between, world_on_date). It stops short of naming any of those alternatives, and the phrasing 'which later changes to a provision reach it' is grammatically tangled, but the intent is recoverable.

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 opening clause 'For a case commenced on one date' fixes the scenario in which the tool is correct, which is implicit usage guidance. However, there is no explicit statement of when not to use it, and no pointer to the adjacent tools an agent might otherwise pick (provision_history for a plain amendment timeline, changes_between for two dates). The choice must be inferred.

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