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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=false, and idempotentHint=true, so the agent knows this is a safe read operation. The description adds context about the data source ('same engine as idevice.com/compare') and the confidence labels (Confirmed/Reported/Our read) with source outlet and date, which is valuable. However, it doesn't mention pagination, rate limits, or error behavior. With annotations covering the safety profile, a 3 is appropriate – the description adds some value but not rich behavioral context.

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 sentences with zero waste. The core function is front-loaded ('Side-by-side specs for 2 or 3 products'), followed by data provenance and optional filtering detail. Every sentence earns its place.

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?

Given the tool's complexity (comparing 2-3 products), the description covers cardinality, data source, confidence labeling, and optional filtering. It omits return format details (e.g., table structure) and doesn't mention the output schema (none exists), but for a read-only comparison tool, it's largely complete. Minor gap: no mention of how missing data is handled across categories.

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 description coverage is 100%, so the schema already documents both parameters. The description adds a concrete example for the specs filter ('battery','sleep') and clarifies that product_slugs can be 2 or 3, but this is largely redundant with schema details. Baseline 3 is correct when 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 (compare) and resource (products) with cardinality constraints (2 or 3). It distinguishes itself from siblings like get_product_facts or get_product by implying a multi-product side-by-side view. However, it doesn't explicitly differentiate from get_compatibility or should_i_buy, which might also involve multiple products.

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?

The description implies when to use this tool (side-by-side specs for 2-3 products), but provides no explicit exclusions or alternatives. Sibling tools like get_product_facts or get_detailed_facts might be confusing without guidance on when to use compare vs. those.

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