Attach a fact to a node

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

Annotations already disclose the mutation profile (readOnlyHint=false, destructiveHint=false, idempotentHint=false), and the description adds real value beyond them: the note does not alter node state or the stack, and it is not itself a node. It does not address what happens on repeated calls despite idempotentHint=false, which is a minor 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?

Front-loaded with the core action, then routing to siblings; roughly three tight clauses with no wasted preamble. The aside 'nobody rereads' is rhetorical flavor that slightly dilutes the density but does not obscure the instruction.

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?

A two-parameter, no-output tool with full schema coverage and annotations present; the description supplies the decision logic an agent needs (note vs. push/pop vs. add) and the non-mutating guarantee. Only the repeat-call/visibility behavior of notes is left unstated, which is a minor omission.

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 description coverage is 100%: the id parameter's 'Defaults to the current focus' and note's 'The fact to attach' are already documented in the schema. The description adds no syntax, format, or length guidance beyond that, so the baseline of 3 applies.

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 ('Attach a fact to a node') and immediately delimits the scope ('without changing its state or the stack'). It explicitly distinguishes itself from vivac_push, vivac_pop, and vivac_add, so an agent can route without opening sibling schemas.

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 positive use case (facts that would otherwise only live in a chat transcript, called alongside vivac_push/vivac_pop) and an explicit exclusion with a named alternative: if the fact 'deserves to be found on its own -- a finding, a measurement' use vivac_add. Both when-to-use and when-not are stated.

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