Read one section of a document

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

Annotations already declare the safe read-only, idempotent profile, so that half is covered. The description adds genuinely useful behavior beyond the annotations: byte bounds (8192 default / 32768 max), truncation signaling via nextOffset, and the explicit failure mode for ambiguous matches returning candidates.

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 densely-worded sentences, front-loaded with the primary behavior and the resolution order. Every clause carries information (precedence, mode switch, bounds, failure), though the packing is tight enough that a first-time reader may need a second pass.

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 9-param read tool with no output schema, the description covers return shape (section text), bounding/pagination (nextOffset), and error behavior (candidates). The main gap is that it doesn't explain how `offset` and `context` interact in practice, but the essentials for correct invocation are present.

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 already 89%, so the baseline is 3, but the description adds real meaning by defining the precedence order among id, anchor, and heading, and by clarifying that `line` switches to a windowed read around a reference. That resolution logic is not derivable from the schema alone.

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 one section's text') and enumerates the exact resolution precedence (id → anchor → heading). It names the sibling docguard_docs_for_path, so an agent can distinguish it from the other read-oriented 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?

Gives clear context for when to use the `line` mode ('the cheapest read for a table row') and names the sibling whose output feeds it. It resolves ambiguity between id/anchor/heading, though it stops short of explicit when-not-to-use guidance versus the full-document alternatives.

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