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

Goes well beyond annotations (readOnlyHint=false, destructiveHint=false). Discloses the full-replace-not-merge behavior, the per-item status model, the visibility/session persistence, and the hard prerequisite that chatid must come from an active chat session and cannot be minted via MCP.

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?

Front-loads the create-or-replace action and the full-list rule. Dense but every sentence carries operational value. Slightly long with the id naming rule tacked on at the end.

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?

No output schema, and the description covers the mutation semantics, status lifecycle, and the chatid prerequisite adequately. The 'never include ids' line sits oddly against the schema's optional id field, leaving slight ambiguity for an agent.

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%, so baseline is 3. Description adds meaningful semantics: full list replaces rather than merges, item fields text+status with enum values, and 'never include ids'. However 'never include ids' conflicts with the schema which allows an optional id for stable ids, which is a minor contradiction.

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 (create or replace) and resource (todo checklist for the current chat), and distinguishes the replace semantics from a merge. Sibling names are mostly accounting tools, so no confusing overlap.

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?

Clearly explains when to use it: planning multi-step work, marking in_progress before starting and done when finished. Also states the prerequisite of an ACTIVE Ask-stub chat session. Lacks explicit when-not-to-use beyond the chatid prerequisite.

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