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

Annotations already establish readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral context: pagination via next_offset, catalog prices retaining original dates and conditions, verified_only limiting results to detailed billing evidence, and catalog-only results not establishing confirmed savings. These disclose nuances beyond the structured annotations.

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?

The description is three sentences, each earning its place: purpose with filter dimensions, pagination and price provenance, and verified_only vs. catalog-only caveat. There is no redundancy or fluff, and the core search function is front-loaded.

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 complex tool with a nested criteria object (14 fields) and zero schema descriptions, the description covers the main search dimensions, pagination, and the important catalog/verified caveat. It does not fully define all parameter formats or explain every filter, but the presence of an output schema and the concise caveats make it largely usable.

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 0%, so the description must compensate. It adds meaning for several key filters (carrier, name/query, network, budget/max_monthly_cents, data/min_data_gb, verified_only) but leaves many criteria fields (age, autopay, bundles, line_count, new_customer, max_prepay_months, etc.) unexplained. This is partially compensating but not fully.

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?

The description states a specific verb and resource: 'Search all published plans' and enumerates filter dimensions (carrier, name, network, budget, data). This clearly distinguishes it from siblings like get_plan_details (specific plan retrieval), compare_plan_costs (comparison), and list_carriers (carrier listing).

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 usage for finding plans matching criteria, but it provides no explicit when-to-use or when-not-to-use guidance, nor does it mention alternatives like get_plan_details or compare_plan_costs. Usage context is only implied by the verb 'search'.

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