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

Annotations already declare destructiveHint=true, idempotentHint=true and openWorldHint=true, so the safety profile is covered. The description adds the crucial replace semantics ('each block you name in `fields` is replaced entirely'), which tells the agent exactly what gets destroyed and complements the destructive hint with real scope detail.

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 tightly packed sentences, front-loaded with the operation, then format, then the read-and-replace semantics. No filler; 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 destructive mutation with nested objects and no output schema, the description covers the replacement semantics and time format well. It omits auth/permission requirements and does not explicitly confirm that unnamed blocks are left untouched, minor gaps given the rich 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 baseline is 3, but the description adds format guidance the schema lacks: accepted time strings like '09:00'/'09:00:00' versus Google's { hours, minutes } objects. That is meaningful input-format information beyond the structured fields.

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 (Set) and resource (opening hours on a Google Business Profile location), which cleanly distinguishes it from the sibling read tool google_business_location_get and the unrelated google_business_location_update. An agent can identify the operation without opening the 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?

Explicitly routes the agent to google_business_location_get to read current hours before writing, establishing the workflow. It stops short of stating when NOT to use this tool or explicitly warning that partial updates require sending the full block, so it is strong context rather than complete guidance.

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