read_text_file

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

Annotations already declare readOnly, idempotent, non-destructive and openWorld, so the safety profile is covered. The description adds genuine behavioral context beyond that: the return shape (UTF-8 text plus truncation flag and token estimate) and the maxBytes truncation mechanism, which an agent needs to know reads may be partial.

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?

Three short sentences with zero filler: capability first, return value second, sibling routing last. Front-loaded and every clause carries information the agent uses.

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-param read tool with a rich annotation block and no output schema, the description covers purpose, sources, return shape and alternatives. The residual gap is the undocumented mimeType parameter and no note on error behavior when a path or URL fails, but nothing else an agent needs to invoke it is missing.

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 only 20% (only maxBytes is documented in-schema), so the description must carry more. It does map the three input modes to path/url/data(base64) and reinforces the maxBytes cap, but it never explains mimeType or why one source should be preferred over another — meaning one of five parameters remains opaque in both places.

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 (read) and resource (plain-text file), then enumerates supported extensions and the three accepted input sources (path / url / base64). It explicitly names the siblings it is not (read_docx, read_pdf, read_spreadsheet), so an agent can route without opening any schema.

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?

Explicitly directs .docx/.pdf/.xlsx requests to the three dedicated readers, which is exactly the sibling differentiation an agent needs. It does not address other plausible overlaps in the large sibling list (inspect_file, scrape_url for URL sources, import_file_to_kb), so while routing is clear, the exclusions are not exhaustive.

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