List Plans

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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=true, and idempotentHint=true. The description adds valuable behavioral context beyond annotations: it specifies the return format options (markdown/json), describes the return content (title, dates, people count, items count), and documents the specific error case for invalid service_type_id. This provides practical usage information that annotations don't cover.

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 perfectly structured and front-loaded: the core purpose in the first sentence, followed by a clean Args section with bullet points, then Returns and Error sections. Every sentence earns its place with no wasted words. The formatting makes it easy to scan and understand quickly.

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 read-only listing tool with comprehensive annotations (readOnlyHint, openWorldHint, idempotentHint) and 100% schema coverage, the description provides excellent completeness. It covers purpose, parameters, return format options, return content, and error conditions. The lack of an output schema is compensated by the clear Returns description. No significant gaps remain for this type of tool.

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?

With 100% schema description coverage, the schema already documents all parameters thoroughly. The description repeats some parameter information (filter options, limit range, default values) but doesn't add significant semantic meaning beyond what's in the schema. It does clarify that service_type_id comes from pco_list_service_types, which is helpful but minimal additional value.

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 clearly states the specific action ('List plans') with the resource ('for a specific service type in Planning Center Services'). It distinguishes from siblings like pco_get_plan (singular retrieval) and pco_list_service_types (different resource type). The verb+resource combination is precise and unambiguous.

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 provides clear context for when to use this tool (listing plans for a service type) and mentions where to get the required service_type_id (from pco_list_service_types). However, it doesn't explicitly state when NOT to use it or name specific alternatives among siblings, though the distinction from pco_get_plan is implied by the plural vs. singular naming.

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