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

Beyond the readOnly/openWorld annotations, it discloses several behavioral traits an agent cannot get from structured fields: a pricing model ($0.002 USDC via x402, Base/Solana/Arc), that failed calls are not charged, that output is model-generated and should be reviewed, and that word targets are only estimates. This is exactly the extra context annotations don't cover.

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?

It is a tight, front-loaded paragraph: purpose first, then constraints, quality caveat, and price. Every clause carries information, though the repeated '10,000 characters' limit slightly duplicates what the schema already states.

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 an output schema present, the description need not explain return values, and it instead covers the decision-relevant gaps: the two input modes, size/depth limits, cost and payment rails, and output quality caveats. Nothing an agent needs to call this correctly 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 description coverage is 100%, so all four parameters are already documented with ranges and defaults in the input schema. The description largely restates those bounds (depth 1-3, at most 12 sections, 10,000-character text limit) without adding syntax or interaction guidance, so the baseline 3 applies.

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 ('Builds an outline') and details the output shape (title, sections, headings, bullet points), which clearly separates it from siblings like text_headlines or summarize. However it never names or routes away from an alternative tool, so it stops short of the sibling differentiation a 5 requires.

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 'for a topic, or from a text you give' phrasing implies the two usage modes and the either/or input choice, but there is no explicit when-to-use versus when-not guidance and no alternatives named among the many text_* siblings. Usage is inferable but not guided.

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