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

Annotations already declare readOnlyHint=false, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds only that exactly one exercise is inserted, with no disclosure of whether 'name' creates a freeform/custom exercise, what happens on duplicates, or whether ordering within the day matters.

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?

A single well-front-loaded sentence with no filler; the parenthetical '(or a range)' is the only mild redundancy against the reps_max schema description. Efficient, though it spends its space on field enumeration rather than the ambiguity that matters.

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 an 11-parameter mutation tool with no output schema and 45% schema coverage, the description is thin: it omits phase, duration/notes semantics, and the name-vs-catalog-id relationship the agent must resolve to 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?

Schema coverage is 45% across 11 parameters; the description names sets, reps/rep-range, load and rest, which covers five fields but leaves name, notes, phase, duration and edb_exercise_id unaddressed. Crucially it never explains how the required 'name' relates to the optional edb_exercise_id, which is the most consequential ambiguity.

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 ('Adds one exercise to a training day of a program') plus the payload fields it handles. It is clearly distinguishable from siblings like add_program_day or add_program_week, though it does not name them.

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?

There is no guidance on when to use this versus update_program_day or apply_catalog_workout, and no prerequisites. The description gives no indication of whether the target day must already exist or how to obtain a dayId (that hint lives only in the schema).

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