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

Annotations already declare idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful context beyond them by clarifying that re-saving replaces the note, but the cryptic 'without a key nothing is saved' clause is unexplained and borders on noise rather than disclosure.

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?

It is a single front-loaded sentence with little waste, and the note-replacement caveat is correctly parenthesized. The trailing 'Without a key nothing is saved' clause is ambiguous and undercuts the otherwise tight structure.

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 3-parameter mutation tool with no output schema, the description covers the core write and the note-replacement behavior, which is adequate. It omits what happens to a previously saved different version, error behavior, and any clear authentication requirement beyond the vague 'key' reference.

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 0%, so the description must carry parameter meaning; it does name all three inputs and correctly marks the note as optional, matching the required list. However it adds no format or constraint detail (the id pattern, the 100/200 character limits) beyond what the schema's type declarations already imply.

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 states a specific verb and resource ('Save a tool id and version to the account's library'), which lets an agent distinguish it from siblings like list_saved_tools and remove_saved_tool. It lacks any explicit sibling differentiation, but the action and target are unambiguous.

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?

There is no guidance on when to use this versus alternatives such as request_tool or list_saved_tools, nor any stated prerequisites. The trailing phrase 'Without a key nothing is saved' gestures at a precondition but never explains it, leaving usage context to inference.

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