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

Annotations already mark the tool as read-only, idempotent, and non-destructive, and the description adds meaningful behavior beyond that: it returns in one round trip, scopes to US utility-scale data, applies a 50-mile proximity filter for coordinates, and discloses the full return structure and data sources. There is no contradiction 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 long but front-loaded with the most important routing decision, and each block serves a purpose: alternate tool routing, use cases, example, parameters, return shape, and exclusions. Some redundancy exists around siting and PPA sizing, which is mentioned twice in slightly different terms.

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 large sibling set, rich annotations, and existing output schema, the description is nearly complete: it covers routing, exclusions, parameter intent, return fields, and data source. It falls slightly short only on clarifying whether state or lat/lon can be omitted or combined, which matters because the schema marks all parameters optional.

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 coverage is 100%, so the baseline is 3, but the description adds practical parameter meaning through the worked example mapping a user question to energy_type=solar and state=TX, and clarifies the semantics of omitting energy_type, state format, and optional lat/lon for nearest projects. A minor gap is that it does not clarify behavior when no state is supplied, especially since no parameters are required.

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 states a specific verb and resource: retrieving US renewable energy capacity, fuel mix, PPA sizing inputs, and RPS context for a state. It explicitly distinguishes the tool from siblings such as execute_plan, get_grid_data, and get_grid_scoreboard, so the agent can select it without inspecting other schemas.

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 gives explicit when-to-use conditions: state-level fuel mix, PPA sizing, renewable-powered data center siting, and RE100/24-7-CFE feasibility. It also provides clear when-not-to-use routing: pair renewables with siting/grid headroom/market shortlist, call execute_plan; use get_grid_data for live generation and get_grid_scoreboard for non-US regions.

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