brain-mcp

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

Annotations provide readOnlyHint=false, destructiveHint=false, and idempotentHint=true. The description adds valuable context: 'Replaces the full content' clarifies the mutation scope, and the update_date flag behavior explains a side effect. It also mentions error handling ('error if not found'). However, it doesn't cover rate limits, auth needs, or confirmation format details.

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 description is well-structured with a purpose statement, behavioral details, and Args/Returns sections. It's front-loaded and efficient, but the Args section could be more specific (e.g., 'params: object with path/title, content, update_date') to avoid redundancy with the schema.

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?

Given annotations cover safety (non-destructive, idempotent) and an output schema exists, the description is reasonably complete. It explains the core mutation, update_date behavior, and error cases. However, it misses details on note identification (path vs. title priority) and doesn't reference sibling tools for context.

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 0%, so the description must compensate. It mentions 'Note path or title, new content, and update_date flag' and explains the update_date default/effect, adding meaning beyond the schema. However, it doesn't detail the path/title conflict resolution, content format, or error semantics for missing notes, leaving gaps.

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 the tool 'Update the content of an existing note' with the specific action 'Replaces the full content', which distinguishes it from siblings like brain_create_note (create) and brain_read_note (read). However, it doesn't explicitly differentiate from brain_move_note (which might update path/title) or mention the note identification mechanism (path vs. title) in the purpose statement.

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 usage by stating it's for 'existing note' and mentions the update_date flag behavior, but lacks explicit guidance on when to use this vs. alternatives like brain_create_note for new notes or brain_move_note for relocating notes. No prerequisites (e.g., note must exist) or exclusions are provided.

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