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

Annotations only declare the mutation/no-idempotency profile; the description adds real value by explaining the downstream effect — the mark appears on every chart spanning that date and is surfaced by home to later assistants. It does not mention that repeat calls create duplicate marks (idempotentHint=false) or how an existing mark is changed or removed, which is the remaining gap.

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?

Two tight sentences: the first covers what is stored and where it appears, the second covers the evidentiary constraint. No filler, and the key restriction is front-loaded alongside the purpose.

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 no explanation, and the description covers scope, persistence, and the user-stated-only rule for a simple three-parameter mutation. Only the duplicate-mark behavior and any edit/delete path are unaddressed, which is a minor omission for this complexity.

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 67% and the description reinforces the date-versus-span distinction that maps to date/end_date, clarifying that a span is one note ('a sick week') rather than two marks. The text parameter's meaning is already documented in the schema, so this is incremental but useful reinforcement rather than redundant restatement.

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 action and resource: keeping a short user-stated note on a date or span that renders on every telo chart covering that date. That is enough to separate it from siblings like arrange_home, home, and report_gap, though it never names an alternative to contrast with.

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 trigger (the user told you about illness, travel, new training, new shoes) and an explicit exclusion ('Only for facts the user stated, never your inference'). It does not discuss overlap with nearby tools such as report_gap, so the routing guidance stops just short of the top mark.

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