set_email_categories

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

With no annotations, the description fully discloses key behaviors: it replaces existing categories, supports clearing via empty array, returns a success confirmation, and errors on nonexistent email IDs. It also advises checking current categories first. This gives a solid understanding of the operation's effects and failure modes.

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 description is concise (4 sentences) and front-loaded with the core purpose. Each sentence adds value: purpose, use case, clearing behavior, return/error behavior, and a pre-check recommendation. There is no redundancy or fluff.

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?

Given the simple 2-parameter tool with no output schema or annotations, the description is quite complete. It covers the action, the replacement behavior, clear option, success/error results, and a workflow suggestion. It could mention potential prerequisites or restrictions, but for this straightforward operation, it is sufficiently complete.

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?

The schema already provides 100% coverage, including descriptions for email_id and categories, with an example and empty array usage. The description adds some context by saying 'color-coded labels' and recommending get_email before modifying, but these are not significant parameter-level details beyond what the schema states.

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 clearly states the tool's function: 'Set categories on an email, replacing any existing categories.' It uses a specific verb and resource, and mentions 'color-coded labels' and 'organize emails,' which distinguishes it from sibling tools like mark_email_read or set_email_flag.

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?

Provides clear context for use: 'Use this to organize emails with color-coded labels.' It also recommends using get_email to check current categories before modifying, and explains how to clear all categories (empty array). However, it does not explicitly mention when NOT to use this tool or name alternatives.

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