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

Annotations only declare readOnly=false, idempotent=false, destructive=false; the description goes further by stating the write-permission requirement and disclosing a non-obvious side effect (optional GA4 sync through the Analytics Admin API). It stops short of explaining what happens with duplicate titles or what the call returns, which matters for a non-idempotent create.

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?

Front-loaded with the verb, resource and an example, then prerequisites and behavior. Most sentences earn their place, though the trailing GA4 Admin API documentation link is largely noise for an agent deciding whether to call the tool.

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 10-parameter mutation tool with no output schema, the description covers permissions, the date/range rule and the GA4 side effect adequately. It is slightly thin on return value and duplicate/repeat-call behavior, but no critical gap prevents correct invocation.

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 already 100%, so 3 is the baseline. The description adds meaning beyond the schema by making the mutually exclusive date/range relationship explicit ("Provide either a single date, or a start and end date for a range") and by clarifying that GA4 sync is conditional on a GA4 connection,

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 (Create) and resource (custom annotation on an AIdata property), reinforced by a concrete example ("Removed noindex from 130 posts"). It also explains what annotations are for, so an agent can tell it apart from get-custom-annotations, get-recent-annotations and update-annotation without opening a 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?

Gives clear when-to-use context (document site changes, campaigns, incidents so future analysis has context) and states the write-permission prerequisite and the date-vs-range choice. It does not, however, explicitly name the alternative update-annotation for modifying existing annotations or state any when-not-conditions.

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