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

With no annotations, the description carries the full burden, and it does disclose two real behaviors: a hard cap of 60 latest periods and that the series title is included in the response. However it says nothing about the PRO/subscription requirement that the access_token implies, error behavior for invalid vectors, or what happens when periods exceeds the cap.

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 compact sentence with the most decision-relevant facts front-loaded ('PRO.' then resource then example then limits). The fragmentary grammar and the unexplained 'PRO.' token cost it a point, but nothing is wasted.

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?

For a 3-parameter tool with no annotations and no output schema, the description covers the essentials (what resource, example ID, period cap, title in response) but leaves the PRO/token requirement, error cases, and the shape of the returned data unaddressed. Adequate but with clear gaps.

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 only 33% (just access_token), so the description must compensate and largely does: the example '41690973' clarifies the expected vector ID format, and 'up to 60 latest periods' explains the periods parameter's meaning and ceiling. The access_token semantics live in the schema, and the discrepancy between the '60' cap and the unlimited 'number' type is not addressed.

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?

The description names a specific resource (Statistics Canada vector) and gives a concrete example ID (41690973), plus the scope of data returned (up to 60 latest periods and series title). The verb is only implied by the fragment structure, and it does not explicitly contrast itself with the indicator or dashboard siblings, but an agent can tell this is the per-vector data retrieval tool.

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?

'PRO.' hints at a paid-tier prerequisite but is never explained, and there is no statement of when to choose vector_series over indicator or dashboard. No exclusions, no prerequisites about the access_token, no guidance on period limits beyond the reported 60 cap.

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