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

Annotations mark this destructive and non-read-only, but the description never explains what it destroys or overwrites — e.g. whether existing extension values are replaced wholesale, or how the required `version` acts as a concurrency check. For a destructive mutation with zero annotation elaboration beyond the flag, this is a real gap.

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 with no filler, but its terseness comes at the cost of substance rather than through efficiency; there is no structure to separate what it does from what it needs.

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 destructive six-parameter mutation with no output schema and no parameter documentation needs the description to carry the load on overwrite semantics, version conflicts, and permissions — none of which are present.

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 0% across six parameters: nothing defines `version` (optimistic lock?), `values` (arbitrary JSON blob?), `extensionId`, or `token`. The one sentence only echoes the words activity/extension/values and adds no format, constraint, or conflict-handling detail beyond the schema.

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?

"Attach validated extension values to an activity" gives a verb and resource, so the broad intent is inferable, but "validated" is opaque (validated by whom, when?) and nothing distinguishes this from siblings like activities_update or activities_add that likely also mutate activity data.

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?

No guidance on when to use this versus activities_update or activities_add, and no preconditions stated (must the extension already exist? must the activity be open?). The agent must guess the routing.

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