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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and a closed world, so the safety profile is covered. The description adds genuinely new behavioral context: the results are computed/derived from the user's catalog and the garden's frost dates rather than stored records, and care tasks carry a rain-skip hint. It does not cover freshness/caching or any auth prerequisites, which keeps it from a 5.

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?

Content is front-loaded: the return contents come first, then the usage triggers. Dense but no filler sentences and no restating of the title. The comma-heavy first sentence is slightly overloaded but still readable.

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?

There is no output schema, so the description must carry the return-value burden, and it does enumerate all the payload parts (windows, zone, frost dates, care tasks). Given zero required parameters and a single optional one, an agent has enough to call it correctly; only ordering/shape details of the aggregated response are missing.

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?

The schema has 100% description coverage for the single 'garden' parameter, including its default-to-first-garden behavior, so the schema carries the semantics. The description only obliquely references 'the garden's frost dates' and adds no format, naming convention, or error behavior beyond the schema. Baseline 3 is correct.

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 specific outputs (computed sowing/transplant windows, zone, frost dates, due care tasks) and their source (plant catalog + garden frost dates), so the agent knows exactly what comes back. It is clearly distinguishable from raw lookups like lookup_planting_windows or lookup_frost_dates because it presents derived/aggregated guidance. It stops short of naming any sibling explicitly, so it lands at 4 rather than 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?

Two concrete user-intent triggers are given in quotes ('what should I plant/start/transplant and when', 'what care is due'), which is strong when-to-use guidance. However, there is no when-not guidance and no alternative tool is named for the overlapping cases (get_season_plan, lookup_planting_windows), leaving routing ambiguous for an agent choosing between siblings.

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