Readability score

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

Annotations already cover safety (readOnly, idempotent, closed-world), and the description adds real behavioral context: the sentence splitter/syllable estimation match the website, an arabicWarning field appears for Arabic input, and the returned hints (long sentences over 20/30 words, passive voice, adverbs) are described. Minor gap: no mention of error behavior for malformed paths.

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?

Front-loads purpose and inputs before the metric list, and each clause carries information. The trailing web-version URL is low value for an agent but does not distract much.

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?

With no output schema, the description usefully previews the return payload (six scores, verdict, average grade level, Hemingway-style hints, arabicWarning). Nothing essential for calling it correctly is missing, though it could state what happens if both or neither of text/path are supplied.

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 baseline is 3, but the description adds the either/or semantics between 'text' and 'path' and notes the file format (UTF-8), which is meaningfully more than the schema's terse property descriptions convey.

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 ('Score') and resource ('how easy an English text is to read') and enumerates the exact metrics produced. This clearly separates it from siblings like text_word_count or ai_text_similarity, which could otherwise be confused with it.

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?

Explains the two input modes ('Give "text" or a text file "path"') and flags the English-only scope with the Arabic fallback behavior, which implicitly tells the agent when this tool is inappropriate. It does not name an alternative tool for non-English or non-readability needs, so it stops short of a 5.

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