Image hosting status (providers, tunnel, store)

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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds valuable context beyond annotations by explicitly stating 'READ-ONLY — never starts a tunnel or downloads anything', reinforcing the safety profile and disclosing the specific side effects it avoids. It also outlines the return shape ({ providers, tunnel, store }). This is more than minimal, though it stops short of deep behavioral details like error scenarios.

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 two concise paragraphs, with the first paragraph front-loading the purpose and components, and the second providing usage guidance and return shape. Every sentence carries informational weight; there is no redundant or filler content. It is efficiently structured.

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 read-only status tool with no parameters and no output schema, the description covers the necessary essentials: what state it reports, when to use it, and the top-level return keys. It could optionally detail the nested structure of providers/tunnel/store, but the absence of an output schema makes the current level of detail acceptable. The sibling context and annotations round out the completeness.

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 tool has zero parameters, so the schema coverage is trivially 100%. Per the guidelines, a baseline of 4 is appropriate. The description does not need to explain parameters; it instead focuses on what the tool inspects and returns, adding value beyond the empty schema.

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 opens with a specific verb-resource pair: 'Report the Image Hosting Layer's current state'. It enumerates concrete components (provider, tunnel, store) and explicitly names the sibling tool line_prepare_image, distinguishing this diagnostic tool from the action-oriented prepare tool. This is a clear, unambiguous purpose.

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?

Provides explicit trigger scenarios: 'Use when line_prepare_image fell back to handoff, a verify failed, or the user asks "why can't it host automatically?"'. This gives the agent direct guidance on when to select this tool and implicitly contrasts with line_prepare_image's role, satisfying the 'when' and 'alternatives' criteria.

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