Show how a memory changed

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds that the lookup is scoped to a single saved key over time, but says nothing about what the history contains, whether it can be sparse or truncated, or how far back it reaches - meaningful gaps for a history tool.

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?

One front-loaded sentence with no filler, and the trigger condition plus examples are exactly what an agent needs. It devotes the entire budget to usage and never states in plain terms what is returned, so it is efficient but not perfectly balanced.

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?

A two-parameter read-only lookup with full schema coverage and clear annotations needs little more than the trigger condition, which is provided. The one remaining gap is the return shape (a sequence of prior values with timestamps), which has no output schema to fall back on.

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% and both required parameters are documented with examples in the schema, so the baseline is 3. The description loosely echoes the categories ('metric', 'deal stage or priority'), but those examples do not match the schema's own example ('account'), adding little and slightly muddying the category vocabulary.

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 states a specific resource and scope: the change-over-time history of a single saved metric, deal stage or priority, made concrete with two example questions. An agent can distinguish it from get_revenue_memory (current values) by the 'over time' framing, though it never names the sibling or says explicitly that it returns a timeline.

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?

It opens with an explicit trigger ('Use this when the person asks how one ... changed over time') and backs it with two representative utterances, which is strong routing guidance. It does not state when-not-to-use or name an alternative tool for the 'current value' case, so it stops short of a 5.

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