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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior. The description adds meaningful context: the data source (World Bank CCKP CMIP6 ensemble), the temporal period (1995-2014), and the fact that no auth is required. This goes beyond the annotations and helps an agent understand what the call does.

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 a single focused paragraph that leads with the core purpose, then lists variables, aggregations, special country codes, and source/auth details. No wasted words, though it could be slightly more structured by separating usage notes.

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 simple read-only query tool with an output schema, the description covers the essential aspects: what it returns, how to specify parameters, special aggregate codes, and data provenance. It does not mention pagination or error handling, but these are not critical given the tool's simplicity.

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 each parameter already documented with units, examples, and enums. The description reinforces some details (e.g., 'all_countries') already present in the schema, but adds little new semantic meaning. The baseline of 3 is appropriate given the rich schema.

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 clearly states it retrieves observed historical baseline climatology (1995-2014 average) for a country, listing the supported variables and aggregation options. It distinguishes from projection/extreme tools by emphasizing 'observed historical baseline', but does not explicitly name sibling tools like world-bank-cckp.climate.projection or extremes.

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 provides clear context for when to use this tool (historical baseline) and includes practical guidance such as using 'all_countries' or 'region_XXX' to fetch multiple geographies. It does not explicitly state when to prefer alternative tools, but the historical focus is implicit.

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