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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states only that the tool favorites a channel, but does not mention that it is a mutation, any authentication requirements, side effects on repeated calls, or what happens to existing favorites. This is insufficient for a state-changing tool.

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 a single, terse sentence with no redundancy. However, it is overly minimal and does not provide structured detail that might help an agent, such as clarifying the ownership context or expected outcomes. It is concise but not necessarily well-structured for informative purposes.

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 single-parameter mutation tool, the description is too thin. It leaves the 'dono' (owner) ambiguous, does not mention authentication or error conditions, and does not describe what happens after execution. Given the presence of auth-related siblings, this lack of context could lead to incorrect usage.

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 schema description coverage is 100%, with channel_id fully documented including an example. The tool description adds no additional meaning beyond the schema, so the baseline of 3 is appropriate. No extra context is provided about the parameter's format or behavior.

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 clearly states the verb 'Favorita' (favorites) and the resource 'canal' (channel), making the tool's action obvious. It is distinguishable from siblings like remove_favorite by name, but the description itself does not explicitly differentiate it from other favorite-related tools. Slight ambiguity around 'para o dono' (for the owner) but the core purpose is clear.

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?

No guidance is given on when to use this tool versus alternatives, nor any prerequisites or exclusions. The description is purely a statement of action without contextual direction, leaving the agent to infer usage from the name and sibling context.

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