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

Annotations already establish a safe read-only, closed-world profile, and the description layers on genuinely new behavior: a hard cap of five results, what each result contains (a sample session from week one plus where to find it in the app), that nothing is changed or purchased, and that ranking is by fit rather than commission. These are the kind of traits an agent could not infer from readOnlyHint alone.

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 trigger condition is front-loaded and each sentence carries distinct information (trigger, result count and shape, safety/no-purchase, ranking policy). It is slightly dense at five sentences, with the pricing and commission reassurances bordering on marketing copy, but nothing is redundant.

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?

An output schema exists, so return structure need not be spelled out, yet the description still previews result content and cardinality. Combined with annotations covering safety and the description covering scope, limits, and ranking, an agent has everything needed to select and call it correctly.

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 71% schema description coverage, the schema already explains most parameters, and the description only glosses 'their sport or goal' and hints at creator via 'coach-built'. It adds no syntax, format, or filtering-combination guidance beyond what the schema documents, so baseline 3 is appropriate.

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 ('search Phorme programs') and gives a concrete example ('a structured volleyball program'). An agent can distinguish it from the singular fetch tool get_phorme_program and from the save_* siblings 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?

The opening clause gives an explicit trigger: 'Use this when the user asks for an existing coach-built training program for their sport or goal.' It signals discovery-oriented intent, implicitly contrasting with get_phorme_program, but never names the alternative or states when not to use this tool, so it stops short of a full 5.

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