Create emoji

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

The description adds valuable behavioral constraints beyond the minimal annotations (readOnlyHint=false, destructiveHint=false) by specifying Discord's 256 KB file size limit and supported image formats (png, jpeg, gif, webp). It also implicitly communicates that this is a write operation via 'Upload', which is consistent with 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?

The description is exactly two sentences, front-loaded with the core action, and every word adds value. It avoids redundancy and provides essential constraints without unnecessary elaboration.

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 simple 3-parameter tool with no output schema, the description covers the core purpose, the source URL, and important technical limits. It lacks explicit return-value or permission details, but these are not critical for correct selection and invocation, especially given the sibling context.

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?

With only 33% schema description coverage, the description compensates by clarifying that image_url is the source URL for the emoji. However, it does not add details for the 'name' parameter (though its purpose is obvious from the property name) or 'guild' (which already has a schema description). The description adds some meaning but not comprehensive coverage.

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 'Upload a custom emoji from an image URL' with a specific verb and resource, clearly distinguishing it from sibling tools like list_emojis, update_emoji, and delete_emoji. It also provides concrete context about file size and accepted formats, making the tool's purpose unmistakable.

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?

The description clearly implies this tool is for creating new emojis by uploading from a URL, and the sibling naming convention (list/update/delete emojis) reinforces when to use it. However, it does not explicitly state exclusions or name alternatives, though the context is sufficient for an AI agent to select it for emoji creation.

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