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

Annotations already establish readOnly/idempotent/safe, and the description still adds real value: not_found semantics for missing-or-invisible records, the visibility scoping rule ('you may view'), and the fact that the returned updatedAt acts as an optimistic-concurrency token. The prompt-injection warning about untrusted CRM field values is genuinely useful security context beyond the structured fields.

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 tight paragraphs: the purpose and the concurrency/not_found behavior lead, and the safety note is a separate short block. Every sentence carries weight, with no restating of the name or annotations.

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 no output schema, the description carries the return-value burden and does state the key returned field (updatedAt) plus the not_found outcome. It does not describe other returned activity fields, but for a single-resource getter the essentials for correct invocation 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 50%: workspaceId is documented in the schema itself, while id is undocumented but self-evident. The description adds no parameter-level meaning (no id format, no cross-workspace notes beyond the schema), so this sits at the baseline for partial coverage.

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 and resource ('Returns one activity you may view') and implicitly distinguishes itself from list_activities by emphasizing the singular record. It also names the sibling mutations (update_activity, complete_activity, delete_activity) it feeds, so the agent can place it precisely.

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?

Gives a concrete reason to call it: to obtain the current updatedAt required as expectedUpdatedAt by the update/complete/delete siblings. It doesn't state the converse (use list_activities to enumerate many), but the when-to-use condition is explicit and actionable.

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