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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and non-destructive behavior. The description adds that the data is from ECCC, keyless, and official, but does not provide additional behavioral traits beyond what annotations cover. No contradiction exists.

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?

The description is four sentences long, each serving a distinct purpose: defining the tool, giving station ID examples, citing the source, and characterizing the data. It is front-loaded with the core functionality and contains no redundant or extraneous 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?

The description covers the key aspects: data content, required parameters, and station identification. However, it omits the 50-day limit on the date range, which is only present in the schema. Including this constraint in the description would improve completeness. The tool is otherwise well-specified given its simplicity and good annotations.

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 the schema descriptions for start_date, end_date, and climate_id are clear. The description reinforces the format of climate_id with examples, but these are already present in the schema's examples array. Thus, the description adds minimal meaning beyond the schema.

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 clearly states it provides daily climate records (max/min/mean temperature, precipitation, snow) from Environment Canada. It specifies the need for a 7-digit climate identifier and gives concrete examples (e.g., '6158355' for TORONTO CITY). This distinguishes it from siblings like current_observations or active_alerts.

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 description advises using a climate identifier from the 'climate-stations collection' and notes it is 'Keyless, official ECCC data.' While it doesn't explicitly state when not to use this tool or list alternatives, the context is clear for its intended use case of historical daily data.

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