todo_add

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

With no annotations, the description carries the burden and does useful work: it discloses the SLUG_EXISTS failure mode and the non-obvious upsert behavior that a done todo with the same slug gets replaced. It still omits auth/permission needs, pagination, and the return shape, but the edge-case semantics are the highest-value disclosure here.

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, no filler, with the core action front-loaded and the failure/replacement caveat immediately after. Every clause earns its place.

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 4-param create tool with no annotations and no output schema, the description covers the action plus the two behavioral surprises an agent would otherwise get wrong. It could still say more about the optional date/importance fields' effect, but nothing critical is missing.

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 75% and the schema documents all four parameters, including date formats and slug pattern. The description adds no parameter-level meaning beyond restating slug uniqueness, so the 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?

Specific verb+resource ("Create a todo") plus slug-based identity, which clearly separates it from read-oriented siblings like todo_list and todo_search. It doesn't explicitly name a sibling (e.g., todo_update) to route away from, so it falls short of 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?

Says nothing about when to choose this over todo_update (which likely also modifies todos) or whether to check todo_search first. The SLUG_EXISTS note hints at a precondition but is framed as an error, not as usage guidance.

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