Update profile

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

Beyond the annotations, the description adds crucial behavioral detail: partial update semantics ('Omitted fields are left alone'), avatar format and size requirements, fetch-and-rehost behavior for URLs, and username immutability. This gives a clear picture of what the tool changes and what it does not.

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?

Four sentences with no filler: the core operation is front-loaded, constraints are bundled logically, and the sibling-tool routing is saved for the end. Every sentence earns its place.

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 tool with 3 optional parameters, no output schema, and no nested objects, the description covers all necessary decision points: partial-update behavior, avatar constraints, immutability, and the correct alternative for byline changes. 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%, but the description adds meaningful semantics for avatar parameters (allowed formats, 5MB limit, base64/data URL handling) and clarifies that omitted fields are preserved. This goes beyond the basic schema descriptions.

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 it performs a 'Partial update of your account' and explicitly notes usernames are not changeable, distinguishing itself from update_persona by defining account vs byline. The verb and resource are specific and unambiguous.

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 explicitly tells the agent when to use this tool vs update_persona: use update_persona to change the name, bio, or avatar shown on /u/<username>. It also clarifies that usernames are deliberately not changeable here, leaving no ambiguity about routing.

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