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

Annotations cover readOnly, openWorld, and idempotent, but the description adds substantial behavior: it describes the return fields (observedTier, gaps), tier rules (T1/T2/T3 conditions), null behavior at T3, and graceful error envelope on backend error or unknown merchant. This is valuable context beyond annotations.

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 front-loaded with purpose, then structured into return fields, the aspirational caveat, usage instruction, tier ladder, null behavior, and error handling. Every sentence adds value, and the length is justified by the complexity of the tier rules.

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 no output schema, the description explains what is returned (observedTier, gaps) and covers edge cases (null at T3, error envelope). It also details the tier ladder and the relationship to actual issued tier, making it complete for an agent to invoke 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 is 0% for the single merchantId parameter, but the description compensates by repeatedly referencing 'merchant' and explicitly mentioning 'unknown merchant' in the error envelope, making the parameter's role clear. The parameter name itself is self-explanatory, so despite no direct parameter description, the meaning is well conveyed.

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 opens with a specific verb and resource: 'Aspirational roadmap to higher credit-tier ceilings for a merchant.' It clearly distinguishes itself from the actual tier computation by stating 'ASPIRATIONAL only — the actual issued tier on a Schema B attestation also depends...', which separates it from sibling tools.

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?

Provides explicit when-to-use guidance: 'Use this on merchant-portal flows asking "what does it take to climb to a higher tier ceiling?"'. Also gives a when-not via 'ASPIRATIONAL only', contrasting with actual issued tier determination. This is clear context with exclusion.

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