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

Annotations already declare non-read-only, destructive, and closed-world behavior. The description adds genuinely new context: the write-scope auth requirement and the downstream effect of grounding future posts. It does not clarify whether an existing file is overwritten or appended, which is the one meaningful behavioral gap.

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?

A single compact sentence with the action front-loaded and no filler. The parenthetical and trailing clauses make it slightly dense, but every element carries information.

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 two-parameter write tool with no output schema and annotations that cover the safety profile, the description supplies purpose, auth requirement, and downstream effect. Nothing essential to invoking it correctly is missing.

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%, so both parameters (path, content) are fully documented in the schema itself. The description only restates the .md path constraint and adds no format, size, or encoding guidance beyond structured data, so the baseline 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?

States a specific verb and resource ('Write one Brand Memory file') and adds scoping constraints (single file, .md paths only). The write semantics clearly separate it from siblings brain_read and brain_tree, so an agent can pick it without opening another schema.

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 it ('the agent grounds future posts in it') and names an auth prerequisite ('needs the write scope'). It stops short of explicit exclusions or naming brain_read as the read-side alternative, so it is strong context without full routing guidance.

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