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

Annotations already establish a safe, read-only, idempotent, closed-world call, so the description focuses on semantics that matter: the full set of verdict values, the evidence words, and the critical rule that 'Not confirmed means unknown, never incompatible.' It also gives user-facing phrasing guidance for 'Works with limits'.

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 purpose, then the return vocabulary, then the parameter note; nothing is redundant. The second sentence is a long enumeration but each clause (limits, requirements, evidence, source link) 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?

There is no output schema, so the description carries return-value semantics and does so thoroughly: verdict values, per-verdict requirements and limits, evidence qualifiers, and the source link. Nothing an agent needs to interpret or present results is missing.

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 100% and the schema documents both fields with examples, so baseline is 3. The description adds behavior beyond the schema by stating that query is optional and narrows results to a single device, implying the unfiltered call returns the full Works with set.

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 and resource ('Whether a product works with a given phone or device') and ties it to a concrete source ('its Guide's Works with tab'). It enumerates the answer vocabulary, so an agent can distinguish it from get_product_facts, get_in_the_box, or compare_products 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?

It explains that the optional query narrows the result to one thing and gives examples, which implies when to use the unfiltered vs filtered form. However, it never names alternatives or states exclusions, e.g., when to prefer compare_products or get_product_facts over this compatibility lookup.

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