update_habit

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

With no annotations, the description carries the full burden, and it does disclose partial-update semantics ('没传的字段保持原样') and that today's count is untouched — genuinely useful behavior. It says nothing about what happens when a nullable field is explicitly set to null (clear vs. ignore), whether the change is irreversible, or what is returned, which are real gaps for a mutation tool with zero annotation coverage.

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 front-loaded sentence enumerating fields followed by the two most important behavioral caveats; nothing is padded. It could be tightened only slightly, and it is not missing structure so much as missing content.

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 six-parameter mutation tool with no annotations and no output schema, the description covers the happy path but omits null semantics, the required id, and any statement of the return value or error cases. It is adequate to attempt a call but not complete.

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 supply meaning, and it only restates the five field names in Chinese without explaining formats, value ranges for color, or the null-clearing semantics that the anyOf[string|null] schema leaves open. The required id parameter is never mentioned.

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 uses a specific verb (改) plus the resource (习惯) and enumerates the editable fields (标题/目标次数/单位/图标/颜色), so the agent can tell it apart from sibling mutators like update_todo and update_countdown. It stops short of an explicit role split against check_habit, but the operation type 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?

The clause '今日计数不受影响' implicitly steers count-related work away from this tool and toward check_habit, which is useful routing. However, there is no explicit when-to-use/when-not statement, no mention of prerequisites such as the habit existing, and no naming of the alternative tool.

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