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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety and side-effect profile is fully covered elsewhere. The description adds only the scope of the resource and discloses nothing behavioral beyond that – no indication of what a 'source' record contains, how results are ordered, or whether pagination applies.

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?

A single front-loaded sentence with zero wasted words. It is appropriately sized for a simple list tool, though the brevity comes at the cost of the guidance noted in other dimensions.

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?

With no output schema, the description is the only place a return shape could be hinted at, and it does not describe what a source entry looks like. For a trivial read-only list tool with complete annotations, this is minimally viable but leaves the query-parameter surface and result format unexplained.

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 100% for the single optional 'query' parameter, so the baseline of 3 applies. However, the parameter is an open-ended object with additionalProperties and no named keys, and the description does not enumerate any supported query fields, so an agent gets no help in constructing useful filters.

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 (List) and a specific resource (upstream sources used for clean air zone decisions), which is enough for an agent to distinguish it from clean_air_check, clean_air_zones, and clean_air_catalogue. It does not, however, explicitly distinguish itself from the parallel road_legal_data_sources or vehicle_data_sources siblings, relying on the name for domain scoping.

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?

There is no when-to-use guidance, no prerequisites, and no mention of the alternative sibling tools (clean_air_catalogue, clean_air_zones, clean_air_check) that an agent might confuse with this one. The description is purely descriptive, so usage must be inferred from the name alone.

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