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

Annotations already declare the call read-only, idempotent, open-world, and non-destructive; the description adds useful behavioral context that is not in the annotations, such as results being measured at the close, the tail being measured against when-issued yield, and bid-to-cover being compared to a twelve-auction average. It stops short of describing result ordering or default limits, but the safety profile is well covered.

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 only three sentences, front-loads the output contents, and then gives usage guidance. It loses a point because the claim that Helious is the only free source publishing tails is promotional and irrelevant to selecting or invoking the tool.

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?

Since there is no output schema, the description compensates by listing the returned metrics, defining the critical tail concept, and explaining the verdict scale. It is sufficient for the stated use case, though minor operational details like default limit and ordering are absent.

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%, so the baseline is 3. The schema already documents limit and offers a rich tenor explanation with examples, classes, and segments; the description's tenor mention reinforces that guidance but adds no new parameter-level meaning beyond the 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 identifies the resource as US Treasury auction results and enumerates the specific returned metrics: high yield, tail versus when-issued, bid-to-cover versus the twelve-auction average, buyer categories, and a strong/in-line/weak verdict. It is distinguishable from sibling curve and rate tools by content, though it never explicitly names an alternative.

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 a concrete query trigger: pass a tenor when the user asks how the last 10-year or 30-year auction went, and explains that the tail is the good/bad signal. It does not name sibling tools or state when not to use this tool, so it falls just short of fully explicit routing.

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