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

Annotations already declare readOnlyHint=true, and the description adds useful behavioral context: the index fuses 'smart-grid load anomalies' with 'satellite land-surface-temperature anomalies' and uses a 'seasonal baseline back to 1895'. It also states 'Updates: daily' and lists output fields, which goes beyond the minimal read-only annotation.

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 compact: two sentences convey the output, methodology, use cases, and update frequency. It is front-loaded with 'Returns a 0-100...' and 'Call when...' with no filler, making it easy to scan.

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?

No output schema exists, but the description compensates by listing all return fields (stress_score, load_anomaly, lst_anomaly, transformer_risk_flag, confidence, methodology_version) and explaining the index's nature. It also covers update cadence and sample use cases, providing a complete picture for a simple read-only tool.

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?

The only parameter, 'days', is fully described in the schema (100% coverage), including range, purpose, and the Gold tier requirement. The tool description itself adds no parameter-level information, so it stays at the schema-driven baseline of 3.

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 identifies the tool's function: 'Returns a 0-100 US cooling-demand grid-stress index' with specific output fields. It distinguishes from siblings by naming the exact resource and scope (US cooling-demand grid stress), which is unique among the listed sibling tools.

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 provides explicit usage contexts: 'Call when the user asks about heatwave grid strain, urban-heat-island load risk, or transformer-failure exposure, or when timing maintenance dispatch, crew pre-staging, or summer O&M budget decisions.' This is clear contextual guidance, though it does not mention alternatives or when not to use, preventing a 5.

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