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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description earns credit beyond that by flagging the semantic trap that a rising level usually means yields fell, and by disclosing provenance — constructed by Safe Rate, not an official Treasury statistic — which matters for how an agent cites the data. Rebalance-date-only constituents is also surfaced in the schema, not repeated here.

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?

Three tight sentences, front-loaded with what the tool returns, then the enumeration and the critical total-return caveat. No filler and no repetition of schema detail.

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 zero required parameters, full schema coverage, and no output schema, the description does the needed work of explaining what comes back (levels, listing, fund comparison). It could be slightly stronger by indicating the shape of a single-index response versus the listing, but nothing essential for correct invocation is missing.

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%, so all five parameters are already documented with patterns and examples. The description adds only the no-code listing behavior, which reinforces the optionality of 'code'; it adds nothing about 'on', 'since', 'include', or 'constituents_on' beyond the schema. Baseline 3 is appropriate.

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 and resource (Treasury total-return indices) and enumerates the coverage space — maturity buckets, bills, TIPS, floating-rate, aggregate. The explicit 'TOTAL RETURN levels, not yields' line separates it cleanly from get_treasury_curve and get_treasury_rate_history, which an agent might otherwise confuse it with.

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?

Gives a clear operational rule — 'call with no code to list every index and discover the codes' — which tells the agent how to bootstrap from an unknown code. It implies the alternative yield tools by contrast but never names get_treasury_curve or says when not to use this one, so routing is inferred rather than stated.

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