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

Annotations cover the safety profile (readOnly, idempotent, non-destructive), and the description goes well beyond them: it discloses that the whole fleet returns in one response with no filters, enumerates returned fields, and warns about distortion behavior (span-annualisation inflating commissioning units 1.5x-2.4x, FCAS-primary inflation, duration bias), null semantics for commercial_context, and peer_comparable pooling constraints. This is unusually rich behavioral disclosure.

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?

Well front-loaded: purpose, then the DUID/usage directive, then the field list, then caveats. However it is very long and some caveat passages (the double-counting/anti-rescaling warning) are dense and repetitive; it could be tightened without losing meaning.

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?

There is no output schema, so the description must carry the return-value burden, and it does: it lists every returned field and explains the two most misusable ones (rev_per_mw_yr, commercial_context/peer_comparable) in depth. An agent has everything needed to call and correctly interpret the result.

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?

Zero parameters, so the baseline is 4. The description contributes field-level semantics (DUID, commercial_context, unit_class, rev_per_mw_yr), but those are return-value concerns rather than parameter meaning, so it does not push above the zero-parameter 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?

States a specific verb+resource and scope: 'Reference list of every NEM-registered grid-scale battery.' It also distinguishes itself from siblings by positioning itself as the resolution step ('turn a station name into the DUID the other tools need'), so an agent can tell clearly what this tool is for versus get_battery_detail or get_rankings.

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 states when to use it ('Call this first to turn a station name into the DUID') and when NOT to use it, naming alternatives: 'use get_battery_revenue over a matched window, or get_battery_optimal for capture' and 'Do not use it to compare units, rank performance.' This is textbook alternative-routing guidance.

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