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

ReadOnlyHint and destructiveHint already identify this as a safe read operation. The description adds useful scope and continuation behavior: it covers exactly one SEC filing or transcript and identifies the next startLine when truncated. The 2,000-line cap is partly duplicated from the schema, but the next-startLine detail goes beyond it.

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 compact sentences front-load the core purpose, then explain how to obtain line numbers, then state the return limit and truncation continuation. Every sentence earns its place with no filler or redundancy beyond the schema's existing 2,000-line limit.

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 simple read-only tool with a fully documented schema, the description provides the missing runtime details: it clarifies the source of line numbers, caps the returned batch, and explains how to continue when truncated. No output schema exists, so the return-behavior note is essential and sufficient.

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%, and startLine/endLine semantics are fully documented in the schema. The description adds the useful hint that line numbers can come from SearchDocument, but this is marginal rather than a substantive expansion of parameter meaning.

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?

The description states a specific verb ('Read') and a specific resource ('numbered lines from one SEC filing or earnings-call transcript'). It also establishes the companion relationship with SearchDocument, making it distinguishable from the search and transcript-retrieval siblings.

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 description gives clear context: use this tool with line numbers from SearchDocument or with a known line range. It does not explicitly list exclusions or alternatives like SearchDocument, so it stops short of full when/when-not guidance.

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