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

Annotations already declare destructiveHint=true and idempotentHint=true, but the description supplies the specifics those hints cannot: the body is replaced whole (what is destroyed), the read-then-resend workaround for appending, the return value, and the OAuth sign-in requirement. This is meaningful context beyond the structured fields.

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?

The primary action, replacement semantics, and sibling exclusion are all front-loaded in the first two sentences, followed by the return value and reference links. No sentence is filler; each carries a distinct operational fact.

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 four-parameter mutation tool with no output schema, every piece an agent needs is present: id provenance, replacement-vs-append semantics, alternative tool routing, auth requirement, and the return shape. Nothing material 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 real value by naming the tools that produce a valid noteId and by clarifying that 'date' relocates rather than edits the note. The full-replacement semantics for 'body' exceed what the schema's 'The full new text.' conveys.

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?

The opening clause names a precise verb (replace), the resource (a day note's text) and a secondary effect (move it to another day), plus the key (note id). It explicitly distinguishes itself from the sibling journal_update_trade, so an agent can route correctly without reading 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?

It states when to use it, where the noteId comes from (journal_get_day or journal_search_notes), and which sibling to use instead for trade notes (journal_update_trade). It also gives an explicit procedural rule for the append case, which is not inferable from the schema.

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