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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior, so the bar is lower. The description adds genuinely useful behavioral context by stating the data source (www.ine.pt open JSON API) and explicitly noting that no authentication is required, which is not captured in the annotations.

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 compact and well-structured: a clear statement of what the tool returns, a directive on when to call it, and a concise data-source/auth note. Every sentence earns its place and there is no redundant filler.

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?

The description covers what the tool returns, the prerequisite relationship to indicator_data, the data source, and the auth requirement. With only two parameters, an output schema, and safety annotations present, nothing essential is missing for an agent to call this tool correctly.

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%, so the schema already documents both parameters and their constraints. The varcd parameter description adds some value with the zero-padded example ('0008273') and clarifies it is an INE code, but it largely repeats the tool-level description and does not materially go beyond the schema.

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?

Description opens with a specific verb and resource ('Get metadata for a Statistics Portugal (INE) indicator by its 7-digit varcd code') and lists the exact fields returned. It explicitly distinguishes itself from the sibling ine-portugal.indicator_data by noting it is the prerequisite step for discovering valid Dim1..Dim6 codes.

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 direct usage guidance: 'Call this BEFORE ine-portugal.indicator_data to discover which Dim1..Dim6 codes are valid for the indicator.' This tells the agent when to use this tool and identifies the relevant alternative, leaving no ambiguity about sequencing.

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