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

Adds substantial context beyond readOnlyHint=false: the consent gate, the calling-user ownership model, sandbox-only execution boundaries, default/capped TTL, and the explicit security caveat that file_request payloads are not yet end-to-end encrypted. This is exactly the kind of limitation an agent needs before calling a mutation 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?

Front-loaded with the core action and return shape, then capabilities, then honest limits — a sensible ordering. It is dense but nearly every clause earns its place; the action_type enumeration slightly duplicates the schema enum.

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 12-parameter, no-output-schema tool, the description supplies the return shape ({action_id, token, link, expires_at}) and delivery mechanics, which is a real gap-filler. The one incompleteness is the missing screen_share action type in prose, which an agent would only discover from the schema enum or the comms_action_frame_get sibling.

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 the schema already documents every parameter including defaults and per-action_type prefixes; the description mostly restates that (TTL default 24h/cap 7d, action_type meanings). It adds little semantic detail the schema lacks, and notably omits screen_share semantics that only appear in the schema.

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 and resource ('Mint a single-use, expiring action link') plus the URL shape and enumerates the action types, so an agent knows exactly what this produces and how it differs from send/message siblings. The only blemish is that the prose lists four action_types while the schema enum has five (screen_share is missing from the description).

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?

Provides clear operational context: the returned link must be delivered via mDM/mIRC/mp0st, the recipient consents in-browser, and each action_type has an inline condition that selects it. It does not contrast against nearby siblings such as comms_embed_create or line_send, so it stops short of explicit when-not guidance.

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