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

Annotations already declare readOnlyHint, openWorldHint and non-destructive behavior, so the bar is lower. The description still adds real context: that results include historical actuals plus an optional forward projection with 75/95/99% confidence bands, which tells the agent what it will receive and that forecasting is opt-in.

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?

Two tight sentences with the core resource and scope front-loaded and no filler. Every clause (bands, segment scoping, valuation complement) carries information.

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, three-parameter tool with a full-coverage schema and an output schema, the description covers the essential shape of the result. It does not point to the discovery tools needed to supply metric_name, a minor omission given the schema references them.

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 all three parameters are already documented in the schema, including the forecast default and the segment/category key. The description only restates that the segment scope and forecast are optional, adding little beyond the structured fields, so 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?

States a specific verb (retrieves) and resource (market metric time series) plus the optional forecast and segment scoping. It implicitly contrasts with siblings like list_market_metrics (which enumerates metric ids) by saying 'for a named market metric', but the differentiation is not made explicit.

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 closing phrase 'provides market context to complement individual valuations' implies when the tool is useful, but there is no explicit when-to-use, no when-not, and no pointer to list_market_metrics/list_market_categories for discovering valid inputs even though the schema references them.

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