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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, covering the safety and mutability profile. The description adds useful context that the source is 'public' daily history and that boundaries are inclusive, but says nothing about range limits, pagination, or partial-data behavior for a potentially large date span.

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 front-loaded fragment with no filler, immediately delivering resource, range semantics, format, and source. It is a sentence fragment lacking an explicit verb ('Returns...'), which is a minor stylistic weakness but costs no comprehension.

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 must convey return shape, and it only implies one record per day via 'Daily' without stating whether a multi-day range yields an array of day entries or how zones are represented. For a simple two-param read with rich annotations, this is adequate but leaves the response contract partly unspecified.

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% and both schema descriptions already state 'YYYY-MM-DD' for first/last day, so the description largely repeats the format. The one genuine addition is the word 'inclusive', clarifying boundary handling, which the schema does not state — enough for a solid baseline but not rich param guidance.

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 returned resource concretely — 'Daily Heat Score and zone between two dates' — and its source, 'the public daily history,' so an agent knows this is a historical daily-metric fetch rather than a live lookup. It does not distinguish itself from siblings like get_market_snapshot or explain_indicator, which is the only gap preventing a 5.

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 statement of when to use this tool versus get_market_snapshot (current state) or explain_indicator (metric explanation). The date-range phrasing implies historical retrieval, but no alternative is named and no exclusion is given, leaving the agent to infer routing.

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