cpu_get_market_index

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

With no annotations, the description fully discloses behavior: server-cached aggregate up to an hour behind, null price meaning 'no trades' not zero/free, and spark series only in JSON not text summary. These are critical semantics beyond the schema.

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?

Though longer than typical descriptions, every sentence earns its place: it front-loads the core purpose, then adds necessary caveats, output formatting details, and sibling differentiation. No fluff or redundancy.

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 no output schema and no annotations, the description is exceptionally complete: it covers all return fields, memory of spark series location, null semantics, caching latency, and comparison with the sibling tool. The tool's simplicity (no params) is fully addressed.

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 schema has zero parameters, so baseline is 4; the description adds meaningful context about the output structure (one row per resource, volume in units not $CPU) and confirms no inputs needed. This goes beyond the minimal baseline.

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 returns a world price index with specific metrics (24h volume-weighted average price, percent change, volume in resource units) and explicitly distinguishes it from sibling tool cpu_get_markets by contrasting 'what the world actually paid' vs 'cheapest ask available right now'.

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?

Provides explicit when-to-use guidance: not for second-fresh data due to server caching, and directly names the alternative tool (cpu_get_markets) with a clear explanation of the different question each answers. Also warns against combining them into one call.

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