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

Annotations already mark this read-only and non-destructive, and the description adds genuinely new context the annotations cannot: the output shape is byte-compatible with three write tools and those write tools overwrite the entire exercise list. That downstream mutation behavior is exactly the kind of trait an agent needs before invoking a read to seed an edit.

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-loads the payload description, then the when-to-use, then the alternative. Every sentence carries distinct information, though the workout_id sourcing is repeated verbatim from the schema and could be trimmed.

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?

The tool is a single-parameter read with an output schema, so return-value documentation is not strictly required, yet the description covers the payload, the call ordering, valid ID sources and the sibling alternative. Nothing needed to call it correctly is missing.

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 description coverage is 100% and the single workout_id parameter is already documented with its valid sources. The description restates the same sourcing guidance without adding syntax, format or constraint detail, so it sits at the baseline for a fully-covered schema.

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 precise verb and resource and enumerates exactly what the response contains (exercises, exercise_id, exercise_type, sets/targets, rest, notes, superset grouping). It explicitly distinguishes itself from the sibling get_workout, which returns a display card, so an agent can choose between them 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?

Gives an explicit read-modify-write workflow: call this before updating because update_custom_workout, update_planned_workout and create_custom_workout replace the whole list, then send the rest back unchanged. It also names get_workout as the alternative for card display and clarifies which sources produce a valid workout_id.

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