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

Annotations only declare readOnlyHint=true, so the description carries the rest of the burden and does add value: it defines the record composition (notes + system events) and the return envelope {count, activity}, letting the agent anticipate entry types. It stops short of stating ordering defaults or volume characteristics, which the schema only partially covers.

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?

Three short sentences, front-loaded with purpose, followed by scope and return shape, then the endpoint. No filler and nothing redundant.

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 supplies the return shape {count, activity} and the entry semantics, and the schema fully documents all six parameters. Minor gap: no mention of pagination strategy or ordering defaults at the description level, though the schema covers those 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?

Schema description coverage is 100%, and the schema already documents from/size/filter/sort/related_id in detail, including the from + size pagination rule and filter examples. The description only reiterates related_id as a contact-or-job scope, so it adds marginal meaning over structured data.

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 ("List") and resource ("activity entries"), and usefully defines what that bucket contains — "notes plus system events such as status changes and record creation" — plus the backing endpoint GET /activities. It does not explicitly contrast itself with sibling note/task tools, so sibling differentiation is left implicit.

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?

"Optionally for one contact or job (related_id)" implies the scoped and unscoped modes, which is enough to pick the call for a contact/job timeline. However, no alternative tool is named and there is no guidance on when to prefer a filtered query versus a broad listing.

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