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

With no annotations, the description carries the full behavioral burden, and it discloses little: only that data starts in 2020 and that access is 'PRO' (implying a subscription). It says nothing about data frequency (monthly? quarterly?), return volume, ordering, or what happens with an invalid token, though the token parameter description hints at auth.

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 short fragments, front-loaded with the tier marker and the core resource/scope. Nothing is wasted, though the terseness borders on under-specification rather than disciplined brevity.

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 one-parameter read tool with no output schema, the essentials are nearly covered, but an agent still cannot tell the data granularity, the response shape, or the size of the history returned. Given no annotations and no output schema, the description should have supplied a bit more about the returned series.

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?

There is a single parameter with 100% schema description coverage, so the schema fully documents access_token and the baseline is 3. The description adds a mild signal that the token is a subscriber credential via the 'PRO' label, but nothing beyond what the schema already states.

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 resource and scope: ABS headline CPI history starting from 2020. An agent can distinguish it from latest_cpi (a snapshot) by the word 'history' plus the start date. It gives no explicit comparison to siblings such as cpi_meta or inflation_group, which keeps it at 4 rather than 5.

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?

The description gives no when-to-use or when-not-to-use guidance and never names an alternative tool. The 'PRO' prefix hints at a premium/paid tier but does not state prerequisites or what to do if the caller lacks access. Only inferred usage is available.

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