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

Beyond the annotations (non-readonly, idempotent replace, potentially destructive), it discloses the default-private posture and that public reviews go through a 'community check' before appearing on the user's page and the title's page. That moderation consequence is real context an agent can't get from the flags; the nature or latency of that check is left vague.

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 short sentences, front-loaded with the operation, then the safety-relevant default, then the pointer to the sibling. No filler or restatement of the name.

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 6-parameter mutation with full schema coverage and no output schema, the description covers the operation, the replace semantics, and the risky visibility choice. It leaves the 'community check' undefined and says nothing about failure modes, which is a minor but noticeable gap.

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 the baseline is 3, but the description earns an extra point by explaining the consequence of the visibility enum (public page + title page after community check) rather than just repeating 'Defaults to private'. Other parameters (spoiler, item_id, media_type) are left entirely to the schema.

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 uses a specific verb+resource ('Write or replace the user's review') and bounds the scope to 'something they have finished', which separates it from delete_review and from the logging siblings. An agent can identify the operation without opening the 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?

It gives an explicit visibility decision rule ('Only make it public when the user asks') and points to update_notes for private jottings, which is a genuine alternative. It stops short of contrasting with update_rating or log_event, so the sibling routing is only partly covered.

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