AI Capacity Index

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

Annotations already declare readOnlyHint=true and idempotentHint=true, so safety profile is known. The description adds context beyond annotations: refresh cadence ('Refreshed Fridays 14:00 UTC'), details on returned fields (facility_count, operator_count, composite score), and data caveat ('where facility data carries them'). No contradictions with 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?

The description is dense but well-organized: purpose, output details, refresh schedule, use cases, and exclusions. Each sentence contributes useful information without redundancy, though slightly long, it remains efficient for the amount of guidance provided.

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 (ranking with composite score) and presence of output schema, the description provides comprehensive context: output fields, refresh timing, use cases, exclusions, and data caveats. It is sufficient for an agent to select and invoke 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?

Input schema covers both parameters (limit and horizon) with full descriptions (100% coverage). The description adds context by mentioning the 30/60/90-day horizon aligning with the 'horizon' parameter, but does not add substantially new semantic detail 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 'ranks data center markets by where 100MW of AI training capacity can land in the next 30/60/90 days'. It uses a specific verb 'ranks' and resource 'data center markets', and distinguishes from siblings by explicitly naming rank_markets and grid_transition_radar as alternatives.

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 explicitly provides when to use the tool ('Use for AI capex planning, GPU cluster siting, hyperscaler deal forecasting') and when not to use it, with alternative tools ('Do NOT use for a general best-markets ranking (use rank_markets) or forward grid-emergence (use grid_transition_radar)').

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