open_sprite

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds two useful facts: it returns the sprite's structure, and in live mode it opens a tab (a visible side effect). It says nothing about failure modes, unsupported-format errors, or persistence, so it adds only modest value over the annotations.

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?

Two compact sentences, front-loaded with the core action and supported formats, then the live-mode caveat. No 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?

There is no output schema, yet 'returns its structure' leaves the return shape vague for a tool whose main purpose is inspection. Combined with partial parameter coverage, an agent knows how to call it but not fully what to expect back.

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?

With 67% schema description coverage, the schema already explains backend (auto/live/batch) and oneFrame, and the required 'file' is self-evident. The description adds no syntax, path, or format constraints beyond what the schema provides, so baseline 3 applies.

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?

States a specific verb and resource ('Opens a sprite file') and enumerates accepted formats, which is genuinely informative. It implicitly distinguishes itself from new_sprite (create) and list_sprites (enumerate), but never names or contrasts those siblings explicitly.

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 'live mode opens a tab' clause hints at when the live path applies, and the backend parameter's enum/description in the schema carries the auto/live/batch logic. There is no explicit guidance on when to choose this over new_sprite, list_sprites, or get_sprite_info, so usage remains implied.

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