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

Annotations already declare read-only, idempotent, non-destructive behavior, so the bar is lower, yet the description adds real context: the sha256 accompanies the content for integrity checking and the content is authored by another participant (an untrusted-input caveat). It does not discuss size limits or failure modes for unverified keys.

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?

Four short sentences, front-loaded with the action and scope before the usage trigger and integrity detail. Minor redundancy between 'shared into a room' and 'written by another participant' but nothing wasteful.

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 an output schema present, return values need not be described, and the description still flags the sha256 verification path and the untrusted-author caveat. The only gap is no mention of what happens when the key is unverified or the fetch fails.

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 both parameters (uuid, file_id) are already fully documented, and the description adds only the vague '(verified keys only)' hint. Baseline 3 is appropriate when the schema carries parameter meaning.

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 ('Fetch the Markdown content of a file shared into a room') with a scope qualifier ('verified keys only'). An agent can distinguish it from list_files (enumerate) and share_file (publish) without opening any 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?

'Use when the user wants to read a shared document' gives a clear triggering condition. It does not name alternatives or state when not to use it (e.g., use verify_integrity for hash checking, list_files to discover file_ids), so it stops short of full routing guidance.

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