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

Annotations already flag this as a non-idempotent, non-destructive write (readOnlyHint=false, idempotentHint=false, destructiveHint=false, openWorldHint=true). The description adds real value beyond that: it says a new Markdown source is created, that title and text are copied from the note, that chat and Studio consume it, and that the response carries the new source id and status — important since there is no output schema. It does not state whether the original note is preserved or what happens on repeated calls.

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?

Three compact sentences, front-loaded with the core transformation, then the return values, then the sibling disambiguation. The trailing 'POST /notes/source' is mild implementation detail that earns little for an agent, but the rest is tight and waste-free.

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 single-parameter conversion tool with annotations present and no output schema, the description covers the operation, the result artifact, the response fields, and the alternative tool. The remaining gap — behavior on repeat calls and whether the note survives — is minor but non-zero for a non-idempotent write.

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% and the single parameter already documents 'Note id, from notebook_list_notes.' The description adds nothing about the note parameter itself (no format, no mention that the id must belong to the same notebook), so the baseline 3 for schema-covered parameters is appropriate.

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 ('turn a note into a source of the same notebook') and immediately explains what the transformation produces (a Markdown source from the note's title and text). It also names the sibling notebook_add_sources and the case where that sibling applies, so the agent can distinguish the two without opening either 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?

Explicitly routes the agent: use notebook_add_sources when the content 'is not a note yet', implying this tool is for existing notes. That is a clear selection rule, though it stops short of stating prerequisites (e.g. the note must already exist and belong to this notebook) or any exclusions such as repeat-conversion behavior.

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