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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the "Read-only" sentence is largely redundant. What the description does add beyond the structured data is real: the warning that a large note produces a large response, and the disclosure that an unknown id yields a "not found" error rather than an empty result.

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?

Four short sentences, front-loaded with the return shape before the usage guidance. Minor waste exists in restating "Read-only" which the annotations already cover, but nothing else is padding.

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?

With no output schema, the description must describe return values and it does so field by field, plus adds the error case and the size caveat. For a single-parameter read tool, an agent has everything needed to call it and interpret the result.

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 the id property already explains the exact format and its origin from brain_search/brain_recall/brain_remember. The description only says "by id", adding no new meaning beyond what the schema provides, so the baseline of 3 applies.

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 opens with a specific verb and resource ("Fetch one note by id") and immediately enumerates what comes back: markdown content, metadata fields, outLinks and inLinks. An agent can distinguish it from brain_search and brain_recall without opening any schema, since those return collections rather than a single fully-expanded note.

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?

It gives two concrete use cases with the alternative named in each: read in full before overwriting via brain_node_update, or follow a link discovered in recalled context (versus brain_recall). The relationship to sibling tools is explicit rather than inferred.

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