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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. With no output schema, the description usefully adds behavioral substance by disclosing what comes back (daily granularity, cumulative GDD at base 10 °C), which the annotations cannot convey. It omits any note on result size, date-range limits, or behavior when a garden has no data.

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: the first front-loads what data is returned, the second routes the agent to the right questions. No filler, no restatement of the title.

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, zero-required-param tool, the description plus a fully documented schema and rich annotations cover what an agent needs to invoke it. The lack of an output schema is partly compensated by the enumerated return metrics, though edge cases (empty history, long ranges) remain unaddressed.

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 parameters ('since' with its 90-day default, 'garden' with its first-garden default) are fully documented in the schema. The description adds no syntax, format, or boundary detail beyond that, so the baseline of 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 gives a concrete verb+resource ('Daily weather history for the garden') and enumerates the returned metrics (min/max temp, rain, growing degree days with cumulative total), which clearly separates it from get_forecast and get_current_conditions by tense/scope. It stops short of naming those siblings explicitly, so it is clear but not fully differentiated.

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 states when to reach for it: '"how warm/wet has it been" and growth-progress questions.' That is a clear usage context with a real user-intent cue. It offers no explicit exclusion or named alternative (e.g. 'for future weather use get_forecast'), so it falls 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.