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

Annotations already declare the tool as read-only, idempotent, and non-destructive, covering the safety profile. The description adds that it returns all themes and their fund counts, which is a useful specificity, but does not disclose any additional behavioral caveats (e.g., potential volume, pagination, or formatting). With annotations present, this is acceptable.

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 two concise sentences with no redundancy. The primary function is stated first, followed by a usage pointer, making it efficient and easy to parse.

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?

Given that the tool takes no parameters, has an explicit read-only/idempotent annotation set, and returns a simple list of themes and counts, the description is complete. An agent has everything needed to decide when to call it and what to expect, with the follow-up tool named.

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?

The tool has zero parameters, so the schema fully covers everything. Per the baseline rule for tools with no parameters, a score of 4 is appropriate; the description correctly does not need to add parameter-level detail.

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 what the tool does: it lists every theme ETFIQ publishes along with the number of funds each holds. It also distinguishes itself from the sibling etf_theme by indicating it precedes that tool, so an agent can tell them apart without inspecting schemas.

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 explicitly states when to use this tool ('Call when unsure what a theme is called') and points to the next action ('then etf_theme'). This gives clear, actionable guidance on the intended workflow and differentiates it from the related sibling.

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