todo_update

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

No annotations are provided, so the description carries the full behavioral burden. It usefully discloses two facts not covered by the schema: updates are partial (unspecified fields are preserved) and the slug is immutable. It omits error behavior, whether updates are idempotent, and what happens when the slug does not match an existing todo.

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, each doing distinct work: stating the operation and scope, defining patch behavior, and flagging the immutable field. The most important constraint (partial update) is front-loaded and there is no filler.

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 four-parameter mutation tool with no annotations and no output schema, the description covers the essentials of update semantics and the slug constraint, which is adequate. It still leaves gaps around prompt and importance handling, invalid-slug outcomes, and return behavior, so it is only minimally sufficient.

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 only 50%: date is richly documented in the schema, but prompt and importance have no descriptions anywhere, and the tool description adds nothing about them. The description does contribute one parameter-level fact (slug immutability), so it adds some value but does not compensate for the undocumented fields.

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 ("Update an existing todo") and adds scope with "open or done," so the agent knows this handles both completion states rather than only pending items. It does not explicitly distinguish itself from siblings like todo_done, which appears to overlap, so it falls short of a 5.

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?

"Only the fields you pass change" communicates patch semantics, which tells the agent it can send partial updates, and "The slug cannot be changed" flags a constraint. However, there is no explicit routing guidance such as when to use this versus todo_done for marking completion, leaving the alternative selection implied.

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