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

Annotations already cover the safety profile (readOnly, idempotent, openWorld=false), yet the description adds non-obvious behavioral limits: prices are dated snapshots from cited sources and NOT live quotes, and currencies are not converted so cross-currency comparison requires an FX rate. It also states the one-market-at-a-time scope, which constrains how results should be interpreted.

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 line and organized into Purpose/Guidelines/Limits/Examples/Scope, so an agent can stop reading at any block. Every sentence carries load: the examples demonstrate valid calls and the Scope line resolves the sibling ambiguity.

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?

Output schema exists, so return-format explanation is unnecessary; the description closes the remaining gaps an agent needs before calling - staleness of data, currency non-conversion, market filtering, and the sibling routing rule. Complete for a zero-required-param read tool of this complexity.

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% with all three parameters documented, so the baseline is 3; the description goes further by framing market as an EU/China narrowing filter and supplying concrete invocation examples (market='cn', market='eu', language='en') that show valid combinations. It adds value beyond the enum labels, though not deep semantic detail on each parameter.

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+scope: 'one-call overview of the carbon market layer' covering price snapshots, market size statistics, and allowance allocation rules with named issuers/sources. It clearly distinguishes itself from compare_carbon_prices, so an agent can route without opening either schema.

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 explicit use cases ('what is the carbon price / how big is the market / how are allowances allocated'), the narrowing action (filter by market), and an explicit exclusion routing cross-market comparison to compare_carbon_prices. Nothing is left to inference.

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