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

Annotations carry the safety profile (readOnlyHint=false, idempotentHint=true, destructiveHint=false), and the description adds useful scope about what is compared. However, the non-mutating language ('re-tests', 'diffs') sits in mild tension with readOnlyHint=false without clarifying that a new evaluation/state is persisted, and it says nothing about what happens if the checkpoint is stale or missing.

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?

Single sentence, front-loaded with the core verb, no filler or restatement of the title. The compound second clause is dense but every element (checkpoint items, the 'what changed since' comparison, the diff-against-current-question mode) earns its place.

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?

With no output schema, the description should ideally say what re-evaluation or a diff yields, and how the 'saved investigation claims' mode maps onto the watch_id/checkpoint parameters — it does neither. For a two-mode, state-affecting tool in a complex finance domain, this leaves the agent able to call it but unsure what it will get back.

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 both watch_id and checkpoint are already documented. The description's mention of 'conclusions recorded at a checkpoint' reinforces what the checkpoint parameter represents, but adds no syntax, format, or default behavior beyond the schema text.

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 specific verbs (re-tests, diffs) on specific resources (conclusions at a checkpoint; a saved investigation's claims) and enumerates what is re-tested: maturity, mark, lenders, performing. This distinguishes it from the sibling watch_changes, though the compound two-mode purpose ('and diffs...') makes it slightly ambiguous whether one or both behaviors fire on any given call.

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 the checkpoint framing ('omit for the first checkpoint'), which hints this is a follow-up to watch creation, but there is no explicit when-to-use guidance and no mention of the obvious alternative watch_changes or changes_since. The agent must infer which of the watch_* siblings to pick.

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