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

Beyond the annotations (readOnlyHint=false, destructiveHint=false, openWorldHint=false), the description discloses the two-step write flow: 'Requires MCP write actions; without confirm:true it returns a preview.' It also discloses the visibility default ('internal, team-only' unless showInReports:true). These are behavioral traits not captured by the 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?

Front-loaded with the core purpose, then backdating guidance, then visibility default, then the confirm requirement — each sentence earns its place with no filler. Dense but efficient.

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 mutation tool with no output schema, the description covers what gets created, the preview/confirm workflow, the visibility behavior, and the write-action requirement. Nothing essential for calling it 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?

Schema coverage is 100%, so the baseline is 3, but the description adds workflow-level meaning: it frames confirm/previewToken as a sequence (preview then apply) and reinforces the showInReports default semantics. It adds value beyond the schema without fully redefining parameter syntax.

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 ('Add') plus resource ('manual timeline annotation') scoped to a client's AI-visibility project, and elaborates with a concrete example ('site relaunch', 'TV campaign started') so the agent knows exactly what artifact this creates. It is clearly distinct from sibling add_* tools (add_market, add_widget, add_tracking_prompt).

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 gives clear usage context — use it to pin explanations onto charts so metric movements are explained, and it says to backdate to the day the event happened. It does not name any alternative tool or state when NOT to use it, so it falls short of the explicit when/when-not/alternatives bar.

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