read_blob

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

There are no annotations, so the description carries the full behavioral burden. It only discloses that images are returned as images, but does not state what happens for non-image blobs, possible errors, side effects, or the actual return representation. Since no annotation confirms read-only behavior, this is a significant gap.

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 consists of three short Japanese sentences, each addressing a distinct aspect: purpose, return behavior, and parameter source. It is front-loaded, contains no redundant words, and is appropriately sized for a one-parameter tool.

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 simple read tool with one parameter, no output schema, and no annotations, the description gives the core purpose, the image return behavior, and the id source. However, it omits non-image return behavior, error handling, and any relationship to sibling tools. With no output schema, the description should more fully explain return values and outcomes.

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 has 0% description coverage for the single required 'id' parameter. The description compensates partially by stating that the id is obtained from a doc, which gives the agent a source for the value. However, it does not clarify the format, constraints, or how exactly to extract the id from a doc, so the compensation is incomplete.

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 action ('blob を読む', read blob) and a key behavior (if it's an image, return it as an image), which makes the resource and purpose clear. It also notes that the id comes from a doc, adding context. However, it does not explicitly differentiate from sibling tools such as render_screenshot, so it lacks strong sibling distinction.

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 phrase 'id は doc から得る' (id is obtained from doc) implies a prerequisite and a context: the tool should be used when a doc references a blob. This is useful but not explicit about when to choose this over alternatives, and no exclusions or alternative tool mentions are provided. It is implied usage rather than concrete guidance.

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