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

Annotations already declare readOnlyHint=false, idempotentHint=true, and destructiveHint=false, so the description does not need to repeat those. However, it adds no extra context about side effects, partial update behavior, or what happens to unspecified fields. It does not contradict the annotations, but it does not enhance transparency either, leaving uncertainty about the update semantics.

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?

The description is a single, efficient sentence with no filler or repetition. It is front-loaded with the action and clearly structured. It earns its place by being concise, even though it may be under-specified.

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?

With 17 parameters, only 24% schema coverage, and no output schema, a tool of this complexity needs a richer description. The current one-sentence description does not explain return values, update behavior, or provide any usage context. It is far from complete for an agent to correctly invoke the tool, especially given the lack of guidance on how to use the many parameters.

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 only 24%, so the description must compensate for undocumented parameters. It mentions 'title, timing, place, or notes' but does not explain those or the other 13 parameters (e.g., price, emoji, stay_id). It adds little beyond the schema's few descriptions, and given the low coverage, this is a significant gap.

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 clearly states the tool's function: changing an activity's title, timing, place, or notes. It distinguishes this from create_activity and delete_activity by using the verb 'change'. However, it only mentions a subset of the fields in the schema (title, timing, place, notes) while the schema includes many more properties like price, emoji, and address, so it is not fully comprehensive but still 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 description gives no guidance on when to use this tool versus alternatives. It does not mention that it is for modifying existing activities or that create_activity should be used for new ones. No exclusions, prerequisites, or contextual advice is provided. The only hint is the name and existence of siblings, which is not explicit guidance.

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