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

Annotations already cover read-only, idempotent, open-world, and non-destructive behavior, so the description's added value is return-field semantics: muscles.main vs muscles.also and the hand-checked main-lift data. It does not describe picture format or how-to step structure, but it meaningfully extends the structured metadata.

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 compact and front-loads the purpose before examples and output details. The opening 'Plan My Workout.' repeats the title and is mild filler, but the rest is efficient.

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?

With no output schema, the description must carry return-value explanation; it names the key returned elements (how-to, muscles, picture) and clarifies the muscles subfields. It leaves some detail about picture or step format unspecified, but is sufficient for a one-parameter lookup.

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 already gives examples for the name parameter, but the description adds that everyday names/aliases (RDL, press-up, lat pulldown) are accepted. That is useful semantic guidance beyond the schema's formal examples.

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 resource and output: one exercise's how-to, muscles, and picture, with example queries. It distinguishes itself from a workout plan by being singular, but it never names planmyworkout_list_exercises or get_workout_plan to route the agent explicitly.

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 gives clear context via example user requests ('how do I do a Romanian deadlift?') and notes alias support. It stops short of explicit when-not or alternative-tool guidance, so an agent must infer that this is for single-exercise detail rather than listing or planning.

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