Add Sticker

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

Annotations indicate this is a write operation (readOnlyHint=false) and non-idempotent, which the description aligns with. The description adds valuable context: URL restrictions, supported formats (png/jpeg/gif/webp/avif), max 8MB file size, and guidance on how to name and tag. This goes beyond the schema and annotations, though it doesn't address failure modes or duplicate names.

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 longer than average but every sentence delivers critical instructions: source restrictions, alternative tool, naming strategy, and supported formats. It is front-loaded with the core purpose and then systematically covers constraints and usage, with no redundancy or 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?

Given the tool's complexity and the presence of an output schema, the description is remarkably complete. It covers the essential context for correct use: what input is allowed, what to do if the image is a file, how to choose name/tags, format limits, and explicit exclusions. The presence of an output schema means return values don't need explanation, so this is fully adequate.

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%, so parameters are already well-documented. The description adds meaningful context beyond the schema: the imageUrl parameter's restriction to public http(s) URLs and explicit prohibition of data:image/base64, plus format and size limits. It also provides strategy for name and emotions parameters (short name, 1-8 tags, use user description if available).

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: 'Add an image to the sticker library from an existing public http(s) image URL only.' It specifies the verb (Add), resource (sticker library), and crucial scope (public URL only), effectively distinguishing it from siblings like create_sticker_upload and add_sticker_by_path.

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 provides explicit when-to-use and when-not-to-use guidance: it warns against data:image/base64, third-party hosts, and directs users with attached image files to create_sticker_upload instead. It also advises on naming and tag selection, instructing to use the user's description to avoid unnecessary visual analysis.

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