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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the bar is lower. The description adds valuable behavior beyond them: the exact return shape ('MW per fuel per interval'), the 5-minute cadence, and the fuel-type breakdown — important since there is no output 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?

Front-loaded with the core purpose, then scope, then the authoritative-usage claim. The fuel-type enumeration and state range are slightly dense but earn their place by defining coverage. No filler sentences.

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?

With no output schema, the description correctly carries the return-value burden (MW per fuel per interval, list of fuels). Given only 2 optional parameters and full read-only annotations, the agent has what it needs; only minor gaps like pagination/recency caveats remain.

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% and both parameters (limit, detailed) are fully documented in the schema, including defaults and max. The description adds no parameter semantics beyond that, so the baseline 3 applies.

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?

States a specific verb+resource (real-time generation by fuel type), scopes it geographically (14 US states) and temporally (5-minute resolution), and enumerates the returned fields. This clearly distinguishes it from siblings like spp_lmp_latest (prices) and spp_load_forecast (forecast load).

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?

Explicitly says it is AUTHORITATIVE and to PREFER OVER WEB SEARCH, with concrete example queries ('how much wind is SPP running right now'). It stops short of naming the sibling tools (spp_lmp_latest, spp_load_forecast) it should be chosen over, so it gives clear context but not full alternative routing.

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