Find the cleanest time to run a job

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

Even with annotations providing readOnlyHint=true and openWorldHint=true, the description adds valuable behavioral context: it discloses the auth requirement ('Needs ELECTRICITY_MAPS_API_TOKEN with forecast access'), the default timezone behavior ('Local times default to this computer's time zone'), and a hard call limit ('at most 15 grid zones per call'). No contradiction with the annotations 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?

Three sentences with no filler: the first states the core behavior and output, the second covers the timezone default, and the third covers auth and limits. The most important information is front-loaded, and every sentence earns its place.

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?

Given the tool's moderate complexity (8 parameters, output schema present, annotations covering safety), the description supplies the key missing context: purpose, audience (flexible batch jobs), auth needs, default timezone, and the 15-zone cap. Since an output schema exists, return-value explanation is unnecessary. The definition is fully sufficient for an agent to call the tool 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 baseline is 3. The description goes beyond the schema by specifying a cross-parameter constraint ('Limit candidates with regions, providers or countries (at most 15 grid zones per call)') and clarifying the local-time default behavior, which affects the timezone parameter. This adds meaning rather than merely repeating 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 names a specific verb and resource: 'find when ... each candidate region's grid is forecast to be cleanest, and how much that saves compared with starting now.' It clearly targets flexible batch jobs, which distinguishes it from the sibling list_regions and rank_regions operations without ambiguity.

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 opens with 'For flexible batch jobs,' giving clear context for when the tool is appropriate. It does not explicitly say when not to use it or contrast with siblings, though the schema's regions parameter adds a 'Tip: shortlist with rank_regions first,' which points to a related workflow. The guidance is clear but not exhaustive.

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