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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description goes beyond by disclosing the estimation method: 'Based on straight-line distance with typical speeds,' which is crucial for setting accuracy expectations. This adds context that annotations cannot convey.

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 exactly two sentences, front-loaded with the core purpose, and includes no filler. Every sentence earns its place: purpose, output scope, and estimation method.

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?

Without an output schema, the description conveys the return content ('times for all transport modes') but not the exact format or units. It also covers the key caveat (straight-line approximation) and origin alternatives. For a moderately complex tool, this is mostly complete, though explicit output structure would improve it.

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 each parameter is already described meaningfully. The description adds the relationship between from_lat/from_lng and property_id ('between a property and a location'), but the schema already notes property_id as an alternative to coordinates. Thus the description adds minimal extra value 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 the tool's function with a specific verb and resource: 'Calculate estimated commute time between two points or between a property and a location.' It also mentions the output scope (all transport modes), distinguishing it from sibling property tools like search_properties or market_stats.

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 gives clear context for when to use the tool (between two points or between property and location) but does not explicitly mention alternatives or exclusions. The uniqueness among siblings makes the usage context implicit, but no direct 'when-not-to-use' guidance is provided.

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