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

No annotations are provided, so the description carries full burden. It adds valuable behavioral context beyond a simple 'fetch': it discloses the cost (0.5 credits) and rate limit (40 calls per rolling hour per account/IP). This helps the agent plan usage. However, it does not describe error behavior or response format.

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 extremely concise: two sentences with zero wasted words. The purpose is front-loaded in the first sentence, and the second sentence provides essential cost and rate-limit info. 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?

For a simple fetch-by-id tool with no output schema, the description covers purpose, cost, and rate limits. However, it omits any description of the return value (what fields the block object contains) and error cases. Given the lack of an output schema, this is a gap that could hinder agent understanding.

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 1 required parameter (block_id) with no description. The description merely says 'by id', which adds no meaning beyond the parameter name. With 0% schema coverage, the description should compensate but does not explain the id format, constraints, or how to obtain it.

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 the action ('Fetch a specific block') and the resource ('by id'). It differentiates from sibling tools like search_blocks (which searches) and get_block_versions (which lists versions). The verb-resource combo is specific and unambiguous.

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 usage when you have a known block id, but it does not explicitly state when not to use it (e.g., use search_blocks if you don't have the id). No alternatives are mentioned. The context is clear but lacks exclusions.

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