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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description adds one useful behavioral fact beyond that: results are scoped to the signed-in reader rather than global. It says nothing about ordering, size, or what happens when the reader follows nothing, but with annotations doing the heavy lifting a 3 is fair.

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 no filler and the key scoping detail ('signed-in reader') placed immediately. It is terse to the point of being a fragment, which costs 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 simple zero-parameter read tool with full annotation coverage, the safety and scoping story is adequate. The gap is the return shape: there is no output schema, and the description does not say whether this returns a list of models with nested market coverage, counts, or status flags, so an agent cannot anticipate the payload structure.

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 tool takes zero parameters, so there is no parameter meaning for the description to supply; the baseline for a parameterless tool is 4. No schema semantics are duplicated or contradicted.

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 conveys the resource (models the signed-in reader follows, plus the markets they cover) but is a bare noun phrase with no verb, and it nearly restates the title 'Your followed models and coverage'. It does implicitly distinguish itself from search_models by scoping to the reader's own follows, but that distinction is left for the agent to infer.

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?

There is no explicit when-to-use or when-not-to-use guidance and no named alternative among siblings such as search_models or follow_model. Usage is only implied by the resource name and the 'signed-in reader' scoping, which is enough for an agent to guess but not enough to route confidently.

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