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

Annotations already establish the safety profile (readOnly, idempotent, openWorld, non-destructive), so the description only needs to add behavioral context — and it does: the response structure adapts to the time range, and accuracy degrades significantly beyond one week. That accuracy caveat is genuinely useful operational information not carried by annotations.

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?

Front-loaded and organized with headers, but it is padded: the adaptive short-term/long-term structure is stated three times (Overview, What You Get, Key Features) and the 'What You Get' bullets overlap heavily. Several sentences do not earn their place against the schema's own descriptions.

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 carries the burden of describing returns, and it does so (temperature, humidity, wind, precipitation, pressure, conditions, summaries) plus the accuracy caveat. Coverage is solid; only pagination/response-size behavior is unaddressed, which is minor for a forecast read.

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 latitude, longitude, startDate, endDate, and the units enum are all fully documented in the schema. The description merely restates coordinates and date range without adding format, boundary, or unit-selection meaning, so the baseline 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?

Opens with a specific verb+resource ('Get weather forecasts for specific locations') and immediately scopes it by response-shape behavior (short-term vs long-term). No sibling tool covers weather, so no differentiation is required, and the intent is unmistakable.

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 'When to Use' section enumerates concrete invocation contexts (travel planning, hotel pages, trip preparation, destination info), which tells the agent what requests should trigger it. However, it names no alternatives and gives no exclusions, so it stops short of full when/when-not guidance.

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