skylight_set_member_avatar

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

The description goes well beyond the destructiveHint annotation by disclosing that without confirm:true it makes no network call and returns a dry-run preview, and that with confirm:true it uploads. It also mentions multipart/form-data and detected MIME type, providing valuable behavioral context an agent needs to avoid unintended changes.

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 dense sentences with no filler. The core action is front-loaded, the alternative is clearly named, and the critical confirm behavior is placed last but clearly explained. 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?

Despite having no output schema, the description tells the agent exactly what to expect: a dry-run preview with resolved image_path and detected MIME, or an actual upload with confirm. It covers the safety-critical behavior, the target resource, and the alternative workflow, making it complete for correct invocation.

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 documents id, confirm, and image_path, covering 75% of parameters. The description adds meaning to image_path by specifying 'absolute path to a local image file' and explains confirm's gatekeeping role. The frameId parameter remains undocumented in both schema and description, which prevents a full 5.

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: 'Set a family member's avatar to a custom photo from a local image file.' It clearly differentiates this tool from the emoji avatar alternative and from related sibling tools by specifying the custom-photo use case.

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 explicitly tells when to use this tool versus the alternative: use skylight_list_avatars + avatar_id on create/update for emoji avatars, and use this tool for custom photo uploads. It also explains the confirm:true requirement and the dry-run behavior without it, giving clear invocation guidance.

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