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

Annotations already cover the safety profile (readOnly, non-destructive, closed world), and the description adds genuinely new behavior: newest-first ordering, the returned field set, the 50-per-call cap with a 20 default, and cursor-based pagination. The <untrusted-text> warning is an important security disclosure about third-party-authored content that no structured field conveys.

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-loaded with the core purpose, then result fields, then follow-up usage, then pagination, then the untrusted-text caveat. Every clause carries information; there is no filler or restatement of the tool name.

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?

With no output schema, the description carries the burden of describing returns (id, name, type, size), ordering, and pagination, and it does all three. Combined with the annotations, nothing an agent needs to call this 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 coverage is 100%, so both limit and cursor are already documented in the schema. The description restates the 1–50/default-20 bound and the next_cursor→cursor handoff, which is helpful reinforcement but adds no semantics beyond the structured data. 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?

Specific verb + resource ('Lists files in the workspace's Media directory'), plus ordering and the fields returned (id, name, type, size). It also explicitly distinguishes itself from the sibling get_media ('Links are left out (get_media has one)'), so an agent can separate the two without opening either 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?

It tells the agent what to do with the results (pass media_id as media in send_message, send_message_batch or create_reminder) and when to prefer get_media instead. It stops short of an explicit 'use this tool when you need to enumerate files, not inspect one' statement, but the routing is clear in practice.

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