read_file

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

Annotations only cover readOnlyHint/openWorldHint; the description adds substantial context beyond them: no vault mutation, the read and its purpose land in the user's private read log, binary files return only a size note, max_chars is capped at 200,000, and lock/missing-path failure modes are named. This is exactly the behavioral disclosure annotations cannot carry.

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?

Roughly three sentences, front-loaded with the core action and then layered with return format, edge cases, and failure routing. Every clause conveys distinct operational information; nothing is padded or repeated from the schema.

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 5-parameter read tool with an output schema, the description covers scope, return shape, binary handling, side effects (read log), limits, and error recovery. An agent has everything needed to invoke it correctly on the first try without consulting siblings.

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 coverage is 100%, so the baseline is 3, but the description adds real meaning on top: max_chars is capped at 200,000 (schema only states the default) and the offset semantics are clarified via 'ending with the offset for the next part when more is left,' implying continuation. Purpose's logging destination is also explained beyond the schema's terse text.

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 ('Read the text of one file in an open vault') and immediately scopes the outcome (text, version line, offset). It is trivially distinguishable from write_file, append_file, and list_folder, which it names or implies.

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?

Gives explicit conditions and remediations: 'Fails if the vault is locked (call unlock) or the path doesn't exist; use find or list_folder to find paths.' It also explains that the version line is meant for write_file when replacing. It lacks a blanket when-to-use-vs-alternatives statement for reading paths you already know, but the failure routing is concrete.

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