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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuine context beyond that: the full shape of the response and an explicit failure mode ('a fund the test cannot be run on says so with the reason'). It does not cover what happens for an unknown or invalid ticker, which is the remaining behavioral gap.

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?

Front-loaded with the core question — whether one ETF delivered what its category promised — before the payload inventory. The dense enumeration of returned fields is long but each clause names a distinct output element rather than padding. It is a single run-on sentence, which costs it the top mark.

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?

No output schema exists, so the description must carry the return values, and it does so comprehensively, including the category-level context and the untestable-fund case. Only the invalid/unknown ticker behavior and the meaning of the numeric index scale are left unstated.

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?

There is a single required parameter at 100% schema coverage, and the schema already gives an example ('such as JEPI'), so the baseline is 3. The description only reinforces the singular scope ('one ETF'), which the schema does not state explicitly but which adds little beyond it.

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?

Names a specific resource ('ETFIQ Promise Index' check for one ETF) and enumerates exactly what comes back: badge (Delivered/Partly/Missed), the number behind it, its window, the fund-page sentence, plus the category's promise, test, thresholds and Promise Index. That is far more concrete than the name alone. It stops short of naming a sibling (e.g. etfiq_methodology for the test definition, etf_scorecard for broader scoring), so an agent must infer the boundary from the content list.

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?

Usage is implied by the phrasing — this is the per-fund check of whether an ETF met its category promise — and the 'one ETF' scope signals it is not a screening tool. But there is no explicit when-to-use/when-not, and no pointer to etfiq_methodology, etf_scorecard or etfiq_page when the agent actually wants the underlying methodology or a multi-fund view.

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