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

Annotations only provide readOnlyHint and openWorldHint, while the description adds substantive behavior: StatCan publication timing, the changed=false response before publication or on unchanged days, disabled SSL verification, and error conditions. This is well beyond the structured hints.

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 front-loaded with the purpose and timing constraint, then structured into Returns and Raises. It is slightly verbose with the HTTP endpoint mapping and full error list, but those details earn their place for an external API tool.

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 still explains the return shape, the no-change case, publication timing, and error behavior. That is enough for an agent to call the tool correctly and interpret the response.

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?

The single vectorId parameter has 0% schema description coverage, so the description must compensate. It identifies the parameter as a series Vector ID, but does not add format, example, range, or source guidance, leaving a minor gap for an otherwise simple identifier.

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: get data points of a series by Vector ID. It also scopes the operation to changes TODAY only and distinguishes the past-release case from the sibling get_changed_cube_list(date).

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?

Explicitly says when the tool applies (today's changes), when it does not return data (before 08:30 ET or no change today), and which alternative to use for past releases. The agent does not need to infer the usage boundary.

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