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

With no annotations, the description carries the full burden. It discloses the weekly granularity, return structure, and method string, which is valuable, but it does not state permissions, error behavior, or whether the operation is read-only.

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 compact and front-loaded with the return format, then defines each parameter efficiently. There is no wasted prose, and the signal examples are presented in a scannable way.

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 three-parameter retrieval tool with no output schema or annotations, the description covers the return shape, all parameters, and the key lookup path. It could be more complete only by explicitly distinguishing this from index_latest and indicating read-only behavior.

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 0%, so the description must compensate, and it does: signal is illustrated with many values, key points to index_catalogue, and since is described as an optional ISO date cutoff. The signal list is not exhaustive due to the ellipsis, but the key parameter is well routed.

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 returns the full weekly history of one series, including the return shape and method string. It distinguishes itself implicitly from index_latest by emphasizing 'full weekly history', but it does not explicitly name or contrast with that sibling.

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?

It gives useful context by pointing to index_catalogue for the key and explaining that since optionally cuts history. However, it does not explicitly state when to use this versus index_latest or other sibling tools, leaving the choice mostly implied.

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