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

Annotations already declare destructiveHint=true, idempotentHint=true, and readOnlyHint=false, but the description adds non-redundant behavior: it replaces rather than merges, the 2000-character cap, and that an empty string clears the notes. These are exactly the operational details annotations cannot express, though return/error behavior past the cap is unstated.

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?

A single dense sentence, front-loaded with the verb and resource, with constraints parenthesized. No wasted words.

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 one-parameter setter with annotations covering the safety profile and no output schema, the description covers scope, mutation semantics, and the size limit. The only gap is failure behavior (e.g., text exceeding 2000 characters).

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 carries the burden for the single `text` parameter, and it does: an upper bound of 2000 characters and the special 'empty clears them' semantics. This meaningfully compensates for the bare schema, though it doesn't say what happens on overflow.

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 names a specific verb (Replace) and resource (the learner's notes for the tutor in the active language), plus the scope qualifier 'active language'. The 'Replace' framing makes clear this is the write counterpart to the read-only `notes` sibling without ambiguity.

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 explicit when-to-use or when-not guidance, and no mention of alternatives such as the `notes` sibling for reading. Usage is only inferable from the verb 'Replace'.

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