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

Annotations already declare readOnly, idempotent and closed-world, so safety is covered. The description adds genuinely new behavior: the API reference can only be read one symbol at a time because the whole file is too large to serve, which prevents a futile bulk-read attempt. It does not say what happens on an invalid or stale path, so it stops short of 5.

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?

The core statement and constraint are front-loaded, and each example line earns its place by mapping a path to its content. The table-style indentation is slightly awkward in a plain description and the 'reading order 1' aside is terse, keeping it just below top marks.

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 docs tool with no output schema, everything needed is present: what is returned, how paths are formed, where to get them, and the one-symbol-per-call limit on API reads.

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 100% and already gives examples, but the description goes further by enumerating the api/component, api/system and api/event path shapes and what each returns, which the schema does not. This is real added semantic value for constructing a valid path.

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 R3 document in full, or one API symbol.' It immediately distinguishes itself from the sibling r3_docs_list, which only supplies paths, and from r3_code_read by being documentation rather than source.

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?

Explicitly routes the agent to r3_docs_list as the source of paths and to r3_docs_list again for how-tos, and even notes a reading order for CODE_PATTERNS.md. The condition for choosing a doc path versus an api/ symbol path is spelled out in the examples.

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