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

Annotations already declare readOnly/idempotent/non-destructive, so safety is covered; the description goes further by disclosing return semantics — per-period granularity, newest-first ordering, both an as-reported and an as-of value, and a restatement flag. That restatement behavior is a non-obvious trait the agent would otherwise not know. It omits pagination behavior and any limits on history depth.

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?

A single dense sentence with no filler, and the ordering constraint is front-loaded. The parenthetical '(and when)' is slightly cryptic and costs a beat of clarity, but nothing is wasted.

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 carries the burden of describing the return and does so reasonably: it explains the row grain, ordering, the two value columns, and the restatement flag. It does not address units, null handling, or what happens when history is shorter than limit.

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 schema already documents as_of, limit, metric, period, and ticker. The description reinforces the newest-first ordering and the as-of cutoff but adds no syntax, format, or edge-case detail beyond what the schema states. Baseline 3 applies.

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 names the resource precisely — a single metric's history, one row per period, ordered newest first — and enumerates the payload fields (as-reported value, as-of value, restated flag). It does not name or contrast with the siblings financials_as_of or snapshot_as_of, so an agent must infer the distinction from the point-in-time wording.

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 stated prerequisites, and no mention of when to prefer this over financials_as_of or snapshot_as_of. The as_of clause hints at point-in-time querying but never tells the agent when that mode is appropriate.

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