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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds genuine behavioral context beyond that: the conditional result shape when there is no active program, and the null semantics for pending_draft when no draft waits.

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 is front-loaded in the first clause, and the sibling-routing sentence is a clean closer. The middle is dense with nested parentheticals and backticked field names, and partly restates what the output schema already declares, so it could be tightened.

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?

Coverage is strong for a read-only, zero-param tool: it explains both the populated case and the degenerate no-program/no-draft cases, and points to the right siblings. Because an output schema exists, the detailed field enumeration is largely redundant, leaving only that minor inefficiency rather than a substantive gap.

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?

The tool takes zero parameters (schema coverage 100%), so there is nothing parameter-level to explain and the baseline of 4 applies. The description correctly implies a no-argument call.

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 (get the active training program) and enumerates the payload: day templates with planned blocks/supersets and per-exercise targets, plus pending_draft. It is clearly distinguishable from siblings like get_coaching_context, review_program_draft and import_document, which it explicitly names.

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 routes the agent away from this tool for adjacent jobs: program-planning data lives in get_coaching_context(task='new_program'), draft validation in review_program_draft, saving/replacing in import_document. What it doesn't spell out is the positive trigger (e.g. 'use when the user asks about their current program'), so it stops just short of full when/when-not guidance.

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