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

Annotations already declare destructiveHint=true, idempotentHint=true and readOnlyHint=false, so safety posture is partly covered. The description adds real behavioral context beyond that: the confirmation gate for editing active plans, and the state semantics of pause ('the policy is kept') vs resume ('re-activate'), plus the dry-run recommendation. It stops short of describing irreversibility or what happens to in-flight routines.

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 core purpose in one clause, then uses compact separator-delimited action breakdowns. Dense but every element earns its place; the parenthetical caveats are tightly scoped. Slightly cluttered by nested parentheses but no wasted sentences.

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 a mutation tool with a nested plan object, no output schema and an undefined return, the description covers action semantics, scope boundaries, confirmation requirements and the preview workflow. Given the schema already supplies field shapes and the linked periodization guide, the remaining gap (no mention of response/confirmation feedback) is minor.

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 67% and the description meaningfully supplements it, explaining what 'plan' is (a policy with phases, step ceiling, deloads) and its boundaries, what each action value means, and the conditional role of 'confirmed'. This adds semantics beyond the enum and nested 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 specific verb+resource ('Change the periodization plan') and then enumerates the three concrete mutations (set/pause/resume) with what each does. It explicitly distinguishes its scope from the sibling save_plan ('it CANNOT define exercises or sets, use save_plan for those'), so an agent can tell the two apart without opening either 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?

Each action carries its own when-to-use condition: set for authoring a steering policy, pause to return to the automatic engine, resume to re-activate. It names the alternative for a related need (save_plan) and the prerequisite workflow (edit an active authored plan needs confirmed:true after user agreement; dry-run first with read_periodization(preview)).

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