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

Annotations already declare destructiveHint=true and idempotentHint=true, so the safety profile is covered. The description adds genuinely non-obvious behavior beyond that: 'Replace' clarifies that the whole list is swapped, and 'Pass existing ids to keep them' tells the agent how to avoid losing existing entries during a destructive replace.

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?

Three short sentences with no filler. The replace semantics lead, followed by the two rules an agent needs. Every sentence earns its place.

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 single complex nested-array parameter with no output schema, the description covers the destructive-replace behavior, id preservation, and the ambiguous days encoding. It stops short of explaining how the nested kinds (commitment/overhead/window) interact, but the schema carries those.

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 schema gives no top-level description for the commitments array and no description for days, so the description must compensate. It does: 'days are ISO weekdays 1=Mon..7=Sun' supplies the encoding that the schema omits, and it explains the days-vs-timesPerWeek tradeoff. It does not cover the many nested fields, but those are documented inside 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?

States a specific verb and resource: 'Replace the list of recurring weekly commitments.' An agent knows exactly what is being mutated. However, it never distinguishes itself from the closely related sibling set_routines, which an agent could easily confuse with weekly commitments.

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 gives an in-parameter rule of thumb ('use timesPerWeek instead when there are no fixed days') and a preservation rule ('Pass existing ids to keep them'), which is useful. But there is no guidance on when to call this versus set_routines or get_commitments, so usage context is only partially covered.

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