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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds two genuinely new facts — the call is free and every model assumption is returned with its source — but says nothing about computation limits, determinism guarantees, or how custom_backend overrides interact with the presets.

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 purpose and the cost signal, then a compact inline field spec and return list; no filler sentences. The telegraphic '?' and brace notation are terse to the point of being cryptic for a first-time reader, which costs it a point.

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?

An output schema exists, yet the description still names the key return values (joules, gCO2e, useful bits, retirement mass, assumptions with sources, Landauer GR1/GR2), so nothing critical is missing on the input or output side. The remaining gap is relational: it never positions itself against certify or green_route for a workflow decision.

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 0% — the single 'workload' object has no documented properties — so the description carries the full burden and does so: it enumerates backend_id with its three enum values, total_tokens, output_tokens, the optional calls/success_score/grid_gco2e_per_kwh/pue, and the nested custom_backend shape with wh_per_1k_tokens. Optionality is marked with '?' and the enum is spelled out, which the schema does not do.

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: computing an energy/carbon footprint for an agent workload, and the 'FREE' prefix implicitly separates it from the paid 'certify' sibling. It never names certify or green_route explicitly, so an agent must infer the boundary rather than read it.

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?

Usage is only implied: 'FREE' plus the word 'quote' signals a no-cost estimate you run before committing to a certificate, but the description never says 'use this before certify' or states any exclusion. There is no explicit when/when-not statement.

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