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

Annotations already declare readOnlyHint=false, destructiveHint=true and idempotentHint=true, so the safety profile is covered. The description adds genuinely useful behavioral detail beyond them: this is a merge-style patch where 'omitted fields keep their values', which is not derivable from the annotation set.

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 sentence with zero filler, front-loaded with the operation and immediately followed by the one semantic detail that matters (partial/merge behavior). Nothing could be removed without losing meaning.

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 mutation tool whose destructive and idempotent traits are already in annotations, the description covers the critical merge semantics. It is slightly thin on the nested 'data' object (field-name conventions, value typing) and says nothing about failure modes for a bad rowId, but no output schema means return values need not be explained.

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 100% and all four parameters (id, slug, rowId, data) are documented in the schema itself. The description only restates that rowId addresses the row, adding no syntax or format detail beyond what the schema provides, 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?

The description gives a specific verb and scope: 'Partially update one row' plus the addressing key 'by rowId'. It does not distinguish itself from siblings like create_collection_row, delete_collection_row or update_collection_schema, but the operation itself is unambiguous.

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?

There is no explicit when-to-use guidance and no mention of alternatives such as update_collection_schema (structure) or create_collection_rows (insertion). The reader must infer that this is the tool for changing values in an existing row.

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