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

The description goes beyond annotations by disclosing that the operation never overwrites because days can hold multiple notes, that it returns the note with its id, and that OAuth sign-in with a LuxAlgo account is required. These are non-obvious behavioral traits that help an agent set expectations, and nothing contradicts 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?

Three sentences with each earning its place: the core action and scope, the distinction from alternatives, and the return/auth information. Front-loaded and free of filler.

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 write tool with three parameters and no output schema, the description covers the key contextual facts: non-destructive append behavior, return value, auth requirement, and clear sibling routing. The schema handles parameter details, so nothing essential 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 description need not repeat parameter details; it only reinforces the date format/timezone, which is already in the schema. It does not add meaning for body or context beyond what the schema provides, 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?

The description states a specific verb and resource ('Add a new note to a trading day') and immediately distinguishes scope: any day, traded or not, and never overwrites. It explicitly separates itself from journal_update_note and journal_update_trade's notes, making the tool's purpose unambiguous among siblings.

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 gives explicit when-to-use ('any day, traded or not') and when-not-to-use: 'to change an existing note use journal_update_note, and for a note about one specific trade use journal_update_trade's notes'. This directly routes the agent to the correct alternative based on the task.

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