Current background details

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

No annotations are provided, so the description must carry the full behavioral burden. It discloses the read-only nature, which is a key behavioral trait, but does not mention potential failure modes, required permissions, or side effects (though there likely are none). For a simple read query, the description is adequate but leaves some unknowns like error conditions and exact return formatting.

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?

A single sentence with no wasted words. The verb 'Report' is front-loaded, and all outputs are listed compactly. This is appropriately sized for the task.

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 zero-parameter read-only tool, the description covers the key aspects: what it reports and the read-only safety. It does not detail return formats or error handling, but given the simplicity and lack of an output schema, it is reasonably complete. The absence of sibling differentiation is a minor gap, but not critical here.

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?

There are zero parameters, so the schema is trivially 100% covered. Per the rubric, a baseline of 4 is appropriate when no parameters exist; the description does not need to add parameter semantics.

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 a specific verb ('Report') and resource ('current background'), and enumerates the exact data returned: canonical local path, source, MIME, dimensions, and size. This distinguishes it from siblings like background_set_local (which modifies) and theme_bg_next (which changes theme).

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 implies it is for querying rather than modifying ('Read-only'), but it does not explicitly name alternatives or conditions for when to use this tool versus siblings. The read-only hint gives some context, but without mention of when to prefer this over, say, background_thumbnail_cache_status, usage guidance is only implicit.

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