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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds an entitlement constraint (starter plan or above) that the annotations do not convey, which is useful. It says nothing about the return shape or whether results are paginated.

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 short sentence with the entitlement constraint placed in a clear parenthetical, no padding or repetition. It is efficient, though the content itself is thin rather than rich.

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 read-only, single-parameter, idempotent tool with annotations covering safety and no output schema, the definition is barely adequate. It communicates the entitlement requirement but leaves the return content ('follows ... and its subscription') only gestured at and offers no sibling differentiation, which is the main gap.

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 100% and the single parameter 'sector' is documented as 'Sector slug'. The description adds no format, example, or meaning beyond that, so the baseline of 3 for fully documented parameters applies.

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 is a verbatim restatement of the title with a parenthetical added, so it duplicates information the agent already has from the name/title field rather than stating what the tool does with a verb+resource. It never clarifies how it differs from the closely named siblings sectors_follow and sectors_unfollow, which is exactly the distinction an agent needs. It reads as a noun-phrase label, not a purpose statement.

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?

It supplies a genuine prerequisite ('needs the starter plan or above'), which is actionable usage context. However, it offers no when-to-use guidance relative to alternatives such as sectors_follow (follow a sector) or sectors_unfollow, leaving the routing decision to inference.

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