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

The annotation readOnlyHint=true already covers the read-only nature. The description adds behavioral context beyond this: formula, 104-week rolling window, weekly updates, data source since 2001, and the meaning of higher scores. This is useful context even though it doesn't discuss edge cases or caveats.

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 sentences, densely packed with formula, output fields, source, frequency, and usage triggers. It is front-loaded with the primary output and avoids fluff, though the first sentence is long and could be split without losing value.

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 tool with one optional parameter and no output schema, the description is highly complete. It explains the metric's calculation, interpretation, update cadence, and return fields, while the schema already covers the days parameter and the Gold tier requirement. The description covers all necessary operational context to invoke the tool correctly.

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 for parameters is 100%, with the only parameter 'days' fully described in the input schema. The description does not add any semantic information about the parameter itself, which is acceptable since the schema already provides the necessary detail. Thus the baseline score of 3 applies.

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 a 0-100 Treasury auction tail stress score with a specific formula (tail_bps z-score minus bid-to-cover z-score), making the verb and resource unambiguous. It also lists returned fields (auction_stress_score, tail_bps, bid_to_cover_z) and the interpretation (higher = weaker auction demand), distinguishing it from any generic stress metric.

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?

Explicit call conditions are provided: 'Call when the user asks about Treasury auction tails, bid-to-cover, weak demand, or whether markets can absorb new debt issuance, or when timing duration trades and order execution around scheduled auctions.' This gives clear context for when to use the tool, though it does not mention when not to use it or name alternative tools.

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