GA4: Create annotation

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

Annotations already declare readOnlyHint=false, destructiveHint=false and openWorldHint=true. The description adds genuinely non-obvious context beyond that: ORANGE is reserved for Google (explaining why the color enum omits it) and that later edits/deletes must go through ga4_admin_request, which usefully signals the created marker is not managed by this tool.

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 action and effect, then the two structural facts an agent needs (date vs range, color reservation). The telegraphic style ('One day (date) or a range (date + endDate)') is efficient rather than wasteful, though slightly clipped.

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 6-parameter write tool with no output schema, the description covers purpose, date-range semantics, a hidden color constraint, and the follow-up path for modification. Missing only auth/property-permission expectations and any note on what the created annotation identifier looks like.

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 83%, so parameter meaning is largely carried by the schema itself. The description reinforces the date/endDate pairing and supplies example titles, but adds no format or validation detail beyond what the schema already states.

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 ('Creates an annotation') and explains the observable effect: it appears in GA4 reports as a marker. Concrete example titles ('Relaunch', 'GTM: Consent Mode v2 live') make the resource unambiguous against siblings like ga4_list_annotations or ga4_admin_request.

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 a clear condition for one-day versus ranged annotations ('One day (date) or a range (date + endDate)') and explicitly routes delete/modify operations to ga4_admin_request. It stops short of naming ga4_list_annotations as the read counterpart or stating prerequisites such as required property permissions.

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