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

No annotations are provided, so the description carries the full behavioral burden. It discloses server-side aggregation/no pagination, monthly vs annual aggregation, local-time bucketing via IANA timezone, production-based emission factors, and zero-emission row behavior. However, it does not disclose the behavior or return structure for negative_price_hours, residual_load, or res_share, leaving part of the tool opaque.

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 well-structured: purpose and use case first, then slug list, per-slug output details, filtering guidance, and two concrete examples. It is slightly repetitive ('no pagination' appears twice) and could be trimmed, but the verbosity is largely justified by the tool's 9 parameters and 6 slugs.

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?

For a 9-parameter, 6-slug tool with no annotations and 0% schema coverage, this is a detailed definition. It covers required slugs, output columns for major slugs, date-range examples, filtering, timezone behavior, and an alternative tool. It remains incomplete for to_zone/from_zone and for three slugs' return semantics, though an output schema exists to fill return-shape gaps.

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 0%, so the description must compensate. It documents slug as an enum-like list, aggregation semantics, zone='all'/list/CSV behavior, psr_types friendly names or B-codes, and tz usage with rich examples. The main gap is that to_zone and from_zone appear in the schema but are never explained in the description.

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?

Opens with specific verbs and resources: 'Compute capture price, capture rate, TBx battery-arbitrage spreads, and other generation-weighted market metrics server-side from landed Parquet.' It enumerates the exact slugs and explicitly contrasts itself with client-side price/generation weighting and with get_tb_spread, so an agent can distinguish it from siblings.

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?

Gives an explicit 'Use this instead of...' instruction for server-side aggregation with no row cap or pagination. It also names get_tb_spread as the correct alternative for single-day top/bottom hour timestamps and directs the agent to list_derivations() for valid slug keys. This makes when-to-use and when-not-to-use clear.

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