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

Annotations already declare readOnly, idempotent, closed-world and non-destructive, so the safety profile is covered. The description adds useful behavior beyond that: the cardinality constraint (2-4 slugs), the row-per-product output shape, and the included fields including reviews. It does not discuss ordering of results or what happens if a slug is invalid, which keeps it short of 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?

Front-loaded with purpose, then the alternative-routing clause, then requirements and return shape, then example phrases. Every sentence carries information, though the trailing phrase list is marginally redundant with the earlier usage sentence.

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?

For a single-parameter, read-only comparison tool with a full output schema and complete annotation coverage, the description supplies everything needed to select and invoke it: scope, trigger, alternative, cardinality, and result shape.

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 already states the 2-4 slug range with minItems/maxItems and the source of slugs. The description's 'Requires 2 to 4 product slugs' restates the schema rather than adding new meaning, so the baseline of 3 applies.

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 ('compares two to four 4OVER4 print products side by side') and enumerates the compared attributes (price, paper, finish, turnaround, rating). This makes it clearly distinct from list/lookup siblings such as show_products or recommend.

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 names the triggering condition ('use it when someone asks which print product to choose') and routes a different question type away ('For two finishes or papers in general use search_knowledge'). It even supplies example customer phrasings, leaving little to infer.

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