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

Annotations declare destructive/openWorld write semantics, and the description goes beyond them with transactional behavior: no screens reached means nothing is created, a failed cast removes the creative, the post auto-expires after expiresInSec, and it requires `creative.create` and `screen.cast`. That is meaningful context an agent cannot get from the annotations alone.

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?

Front-loads the one-step atomic behavior, then stacks behavior, return value, alternatives, and permissions in dense but non-redundant sentences. Slightly packed, but no sentence is 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?

Despite an output schema existing, the description still explains the one return value that matters operationally (castId feeding end_cast). For a 7-parameter mutation with rollback semantics, nothing an agent needs to invoke it correctly is missing.

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 every parameter is already documented in the schema (including enum meanings and cross-references to search_screens/list_items). The description reinforces the headline+body+tone composition and the expiresInSec lifespan but adds no new syntax or constraints. Baseline 3 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?

States a specific verb+resource ('Write a short text announcement and show it on screens in ONE step') and explicitly positions itself against siblings ('Use cast_content to show content that already exists, trigger_emergency_template for an emergency'). An agent can pick it apart from cast_content without opening the schema.

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?

Gives explicit when-to-use routing to two named alternatives and states the selection condition for each (existing content vs. emergency). It also covers the follow-up case: pass castId to end_cast to take the post down early.

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