read_block

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

With no annotations, the description carries the full burden. It explains the core behavior and source disambiguation, but does not disclose what happens when key_path is omitted or when the desired block is not found. The read-only nature is implied but not explicitly stated, and edge-case behavior is absent.

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: a one-sentence purpose followed by three parameter lines, each with a brief explanation and example. Every sentence earns its place, with no fluff or repetition.

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 relatively simple read tool, the description covers all parameters and the primary use case. It leverages the existence of an output schema, so no return-value explanation is needed. Minor gaps exist around edge cases (e.g., null key_path), but overall it is adequately complete.

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?

Schema description coverage is 0%, so the description fully compensates. It provides meaningful explanations and examples for all three parameters: file path, key_path walk, and source disambiguation. This adds significant value beyond the bare type/default information in the input 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: 'Read one block out of a script file'. The phrase 'instead of the whole thing' differentiates it from tools that parse entire files, making its scope clear and distinguishing it from siblings like parse_script.

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 use cases by saying 'instead of the whole thing', suggesting this tool is for when only a single block is needed. The 'source' parameter is explained with an explicit conditional ('when the same path exists in both'), giving clear context. However, it doesn't explicitly name alternative tools or state when not to use this tool.

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