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

Annotations already cover the read-only, idempotent, non-destructive profile, so the description's job is to add context — and it does: data provenance (10 years of weather records), an auth note (works without a Siltwell account), and output format (MM-DD). It does not discuss latency, rate limits, or fallback behavior when coordinates and place conflict, but the essentials are present.

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?

Three tight sentences with no filler: the deliverable first, then the account/format constraints, then the sibling alternative. Every sentence earns its place and the most decision-relevant information is front-loaded.

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 name the return values, which it does completely (spring frost, fall frost, hardiness zone) and even specifies the date encoding. Auth requirements and the sibling boundary are also covered, leaving nothing an agent needs to call this correctly.

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 the schema already documents place, latitude, and longitude with the 'give lat/long instead of place' rule. The description adds the MM-DD date format but no parameter-level guidance, so the 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?

States a specific verb (lookup) and exactly what is returned: average last spring frost, average first fall frost, and hardiness zone. It explicitly distinguishes itself from the sibling get_plan by contrasting the generic place lookup with the signed-in user's microclimate-adjusted garden values.

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?

Names a concrete alternative (get_plan) and the condition that selects it (the signed-in user's own garden, where microclimate adjustment matters), plus that no account is required. It does not differentiate against the other frost/season-adjacent siblings (lookup_frost_risk, lookup_growing_season, lookup_planting_windows), which leaves some selection ambiguity.

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