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

Annotations already carry destructiveHint=true and readOnlyHint=false, so safety is covered; the description still adds real behavior the annotations can't express — unique-match requirement, the replace_all escape hatch, and that an empty new_text deletes content. It omits what happens on a failed/no match and whether the edit is atomic.

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?

Three tight sentences, front-loaded with the action, then the matching contract, then the edge case. No filler and nothing repeated from the schema.

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 destructive mutation tool with no output schema, the description covers the failure-prone behaviors an agent needs (exact copy, single occurrence, deletion via empty string). Missing only error/return behavior on no-match and multi-match without replace_all.

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 only 20% (just workspace), so the description must carry the load, and it does: old_text matching semantics, new_text empty-string deletion, and the role of replace_all are all explained in prose. Only `path` is left to obvious inference.

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 precise verb+resource+scope: replace old_text with new_text in an *existing* note, which implicitly separates it from creation tools. It never names the adjacent siblings it competes with (write_file, append_file), so an agent must infer the boundary rather than read it.

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?

Gives a concrete precondition ('old_text is copied exactly from read_file') and the escalation path when the condition fails ('add context, or replace_all: true'). No explicit when-not-to-use or named alternative among siblings, so it stops just short of a 5.

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