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

Annotations already declare this is read-only and non-destructive; the description adds useful behavioral context by stating the output is the heading tree, not page content, and that each entry includes text, path, depth, and first page. No contradiction with annotations.

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?

Two focused sentences, with the main purpose front-loaded. The fetch composition note is dense but earns its place because it tells the agent exactly how to use the result.

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 single-parameter, read-only tool with an output schema, the description covers purpose, output structure, prerequisite (indexed document), and integration with fetch. Nothing essential 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?

The schema already documents the document parameter fully (exact source file name from search, with an example), so the description adds little beyond that. A baseline of 3 is appropriate because schema coverage is 100%.

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: 'Return the heading tree (table of sections) of an indexed document'. It clearly frames the tool's role as structure exploration, distinguishing it from sibling fetch and search tools.

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?

Provides clear usage context: explore the heading tree before fetching pages, and passes returned page references to fetch with explicit syntax. It does not spell out when-not-to-use or name alternative tools as exclusions.

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