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

Annotations already declare readOnlyHint=true, so the safety profile is covered structurally, yet the description adds real value beyond that: the permission constraint that only the human can change the setting. It does not describe behavior when no routine is configured, but the added auth context is meaningful.

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?

Two tight sentences with no waste; the read purpose is front-loaded and the permission caveat follows. Every clause 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?

An output schema exists, so return values needn't be spelled out, and the description still conveys the gist (enabled + local time). For a zero-param read tool with annotations, this is essentially complete, with only minor gaps like behavior when no routine exists.

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, so the description carries no parameter burden and the baseline of 4 applies. It correctly describes the two conceptual values returned rather than inventing inputs.

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 ('Read') and resource ('daily routine') and even names the two fields returned: the enabled flag and the local time. It is immediately distinguishable from write-style siblings, though it does not name any sibling tool (e.g. agent.routine.briefing) to differentiate scope explicitly.

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?

'Only the human can enable or change it through Settings' tells the agent this is read-only and that mutations belong to the human via Settings, effectively excluding the write path. There is no explicit 'use this when...' trigger, but the read-only context is unambiguous.

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