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

Annotations already declare a destructive, non-read-only mutation, so the bar is lower; the description nevertheless adds real behavioral context: the caller must be the Space owner, only plain text is accepted, and an AI is forbidden from setting provenance to 'real'. That last point is a genuine policy constraint not recoverable from the annotations.

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 compact sentences, no filler, with the ownership precondition front-loaded. Brevity is not the problem here — the omission of parameter detail is.

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?

A 14-parameter destructive mutation with zero schema descriptions and no output schema needs substantially more documentation than two sentences. An agent cannot determine what most fields mean, whether partial updates are allowed, or what happens to unspecified fields.

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?

With 14 parameters at 0% schema coverage, the description carries the full burden and largely drops it. Only provenance ('may not mark it real') and a vague 'plain text only' hint at any parameter meaning; when, where, whoFor, bring, groundRules, finding, firstTime, concernRole, and token are entirely undocumented in both schema and description.

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?

"Change an activity" gives a verb and resource, but 'change' is generic and never says which aspects are editable (the schema hints at many: title, when, where, bring, groundRules). It also fails to distinguish this from the sibling activities_set_details, which plausibly does something similar.

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 phrase 'as its Space owner' weakly implies an authorization precondition, but there is no explicit when-to-use guidance, no exclusions, and no routing to alternatives such as activities_set_details or activities_add. The agent is left to infer the boundary.

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