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

Goes beyond annotations by warning that some updates immediately change live behaviour (e.g. overwriting a live pricing equation) and that the response reports when that occurred — a genuinely useful side-effect disclosure that annotations (destructiveHint only) cannot convey. It stops short of stating whether updates patch or replace existing fields, or what permissions are required.

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?

Two sentences, front-loaded with the create/update rule and the live-behaviour warning placed last where it belongs. The 14-entity enumeration is duplicated verbatim in the entity schema description, which is the main redundancy.

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?

Covers the entity set, field discovery, upsert branching, and the live-side-effect caveat for a 3-param nested-object write with no output schema. The notable gap is whether the 'data' object merges with or replaces the existing row on update — a critical question for a partial-update write tool.

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 description's id guidance and describeQueryableFields pointer largely restate what the schema already documents for id, data, and entity. It adds little new semantics beyond confirming the create/update switch, so 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 precise verb pair and resource: 'Create (no id) or update (with id) one row of a writable entity', and enumerates the entities. The 'one row' scope cleanly separates it from bulk-write siblings like import_write, and the entity list separates it from query/delete.

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 gives the branch condition that selects create vs update (presence of id) and routes field discovery to describeQueryableFields(entity). It doesn't say when to prefer import_write or when a write should be avoided, so it falls short of full when/when-not guidance.

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