Read a chunk

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

With no annotations, the description fully carries the burden of disclosing behavior. It reveals the side effect of updating reading progress and explains the Omit-chunkId-to-continue-from-progress behavior. It does not cover potential errors or authentication needs, but is adequate for a read operation.

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 sentences without fluff. The first sentence states purpose, the second details the two invocation modes and side effect. Every part earns its place.

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?

The description adequately covers the tool's core behavior and side effect for a simple read tool with two parameters and no output schema. It could mention the return type (text) explicitly, but given the straightforward nature, it is nearly complete.

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 description adds meaning beyond the schema: it explains that omitting chunkId continues from the last-read position. However, bookId remains only implicitly tied to identifying the book. The schema already describes chunkId, so the description offers marginal value over the 50% schema coverage.

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 clearly states 'Read the text of one chunk,' specifying a concrete verb and resource. It distinguishes itself from siblings like list_chunks (which lists metadata) and read_notes (which reads notes) by focusing on chunk text content.

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 implies two usage modes (by chunkId or from progress) but does not explicitly state when to choose one over the other or contrast with sibling tools. No direct exclusions or alternative recommendations are provided.

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