todo_update

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

With no annotations, the description carries the full behavioral burden: it discloses that this is a partial update (either field may be omitted) and that it returns the updated list. It does not cover what happens on an unknown id, whether status values are validated, or whether changes are persisted/reversible — real gaps for an un-annotated mutation tool.

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 that front-loads the verb, then the mutable fields, then the return behavior. No filler or 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?

For a 3-parameter tool with an output schema already describing return values, the description supplies the missing pieces an agent needs: the status enum and the fact that updates are partial. Only error/failure behavior is absent, which is a minor gap at this complexity.

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 0%, so the description must compensate; it does the most valuable thing by enumerating the legal status values (pending, in_progress, done), which the schema itself leaves as an unconstrained string. 'id' and 'text' remain undescribed, but their meaning is largely self-evident from the sentence.

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+resource ("Change a todo's...") and enumerates the mutable fields (status, text), which unambiguously separates it from todo_add, todo_remove, and todo_list. It does not name those siblings explicitly, but the operation is clear enough to select correctly.

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?

The word "Change" plus "and/or" implies this is the tool for modifying an existing todo, so usage is inferable. However, there is no explicit guidance such as when to use this versus todo_remove or todo_add, and no statement of prerequisites (e.g., the todo must already exist).

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