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

Annotations only say it is a non-read-only, non-destructive, closed-world write; the description adds what the annotations cannot: zone and % targets are stored portable and resolved per athlete at apply time, the response is a normalized template plus a human-readable summary, and multi-write batches require a plain-language recap and user approval before re-sending. Nothing here contradicts readOnlyHint=false.

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?

Purpose and the template-vs-scheduled distinction are front-loaded, and the denser batch-protocol paragraph is placed last where it belongs. It is tightly written but the middle sentences stack three separate rules (portability, comment fallback, batch threshold) into one block, costing a little scannability.

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 18-parameter tool with deep nested workout nodes and no output schema, the description covers creation scope, library targeting, the portability contract that governs every target, the escalation path for bulk operations, and the return shape. The remaining details (field-level formats, enum values, required category) are fully documented in the schema.

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%, so the schema already carries per-parameter meaning (team defaulting to personal, category being required for library visibility, sport/zone/metric quoting rules). The description still adds cross-cutting semantics: the portability model for zone/% targets and the instruction to route unexpressible intent into node comments rather than approximate it into another field. Incremental, but real value beyond the 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?

The description opens with a specific verb and resource ("Create a reusable workout template in the coach's library") and immediately scopes it against the calendar-based siblings: "A template has no date and no athletes — schedule it later with apply_training_frame." An agent can distinguish this from create_planned_training or update_training_frame without opening any 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?

Explicit routing in both directions: use apply_training_frame later to schedule, and if the request expands past three writes, do not loop this tool — batch through nolio_api_write with dry_run=true and a confirm_token. It also gives a fallback rule for details the schema cannot express (put them in a node comment, never approximate or drop). This is unusually complete when-to-use guidance.

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