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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is clear. The description adds useful behavioral context about what state is reported: freshness, failures, and changelog. No contradiction exists between the description and annotations.

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?

The description is brief, but it front-loads a full JSON-RPC example for `whoami`, which is a different tool and irrelevant to understanding `whats_changed`. This makes the opening confusing and poorly focused. The actual purpose appears after that clutter, and the useful since-example is at the end.

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 tool with one optional parameter, strong annotations, and no output schema, the description adequately covers what the tool returns and when to invoke it. It lists the key pieces of information reported and gives a usage example. The irrelevant `whoami` example hurts clarity but does not leave a critical gap.

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 input schema already provides 100% coverage by describing `since` as an ISO-8601 date/timestamp and stating to omit it for current state. The description adds only an example value (`since='2026-08-01'`) and the note that nothing is needed, which is helpful but not substantial beyond 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?

The description clearly states what the tool reports: index build time, last fetch times for operator sources, changed/failing sources, and a dated changelog. The phrase 'The cron check before regenerating a config from this data' further defines its role. It does not explicitly distinguish itself from the sibling `changes_since`, but the description gives enough functional specificity.

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?

The description says this is the cron check to run before regenerating a config from this data, which is a concrete use case. It also says 'FIRST CALL, needs nothing,' indicating it can be invoked without parameters. However, it does not mention when not to use it or how it compares to alternatives like `changes_since`.

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