Data change probe

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

Annotations already declare readOnlyHint and idempotentHint, so safety needs no restating. The description adds genuine value beyond them: precisely what is returned (global seq plus settings/files sub-counters), the cost claim, and the interpretation rule that an unchanged counter means no change occurred.

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, front-loaded with the cost/semantics claim. The trailing 'Widgets read it for adaptive polling' is mildly consumer-oriented rather than agent-oriented, but it does convey the intended use pattern without bloat.

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 need not be documented, yet the description still summarizes the return shape and interpretation. With zero params and full annotation coverage of the safety profile, nothing an agent needs to invoke this correctly is missing.

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 baseline is 4; the description correctly spends no words on parameter syntax. There is nothing for it to compensate for.

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: it returns the store's global change counter (seq) plus settings/files sub-counters. The phrase 'the cheapest possible change check' implicitly distinguishes it from heavier change-listing siblings like data_changes, but it never names that alternative, so sibling differentiation is left to inference.

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?

Usage is only implied: 'An unchanged counter means nothing in the store changed' and 'Widgets read it for adaptive polling' suggest polling-before-expensive-work, but there is no explicit when-to-use versus data_changes or any exclusion. Adequate context, no routing.

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