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

Annotations (readOnlyHint, idempotentHint, destructiveHint=false, openWorldHint=false) already carry the safety profile, so the bar is lower. The description adds genuinely useful operational context: it is a multi-instrument, side-by-side comparison over a defined field set rather than a single-record lookup, which is not derivable from the annotations. It stops short of stating cardinality limits or partial-failure behavior, hence not a 5.

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?

Two sentences, front-loaded with the action, then the routing guidance. The field enumeration is long but every item is decision-relevant information, not filler.

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 annotations covering safety, 100% schema coverage on the single parameter, and an output schema present, the description need not explain return values or the input format. It supplies the one thing structured data cannot: why and when to choose this over repeat calls to get_product_details.

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?

One parameter with 100% schema description coverage, including a concrete example and min/maxItems constraints (2-6). The description's 'two or more instruments' only echoes what the schema already declares (minItems: 2), so it adds no meaning beyond the schema. Baseline 3 applies when the schema does the heavy lifting.

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 ('put two or more instruments side by side') and resource, and enumerates the exact comparison fields (yield, risk, minimum, custody, KYC gates, target/area, issuer, verification date). It also names the sibling it replaces (get_product_details), so an agent can separate it from the other compare_* tools without opening a schema.

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?

Explicitly scopes usage to "X vs Y" questions and names the alternative (get_product_details repeatedly) that this tool is meant to supplant. The when-to-use and the reason to prefer it over a sibling are both stated, leaving nothing to inference.

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