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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=false, so the mutation profile is known. The description adds genuinely useful context beyond that: the change is in-place, preserves the same dose, and is reversible via undo_last_change. It doesn't disclose failure modes or what happens to dependent lines.

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 front-loaded sentence that leads with the usage trigger and packs scope, dose preservation, in-place semantics and the undo path without waste.

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 two-parameter mutation with no output schema, the description covers the operation's effect and its reversal, which is what an agent needs to act. It omits edge-case behavior (e.g. what happens if the accord holds nested accords or the line is already decomposed).

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% for both parameters (line: name or id; formula: id from list_formulas or exact name), so the schema carries the semantics. The description adds no additional parameter-level detail, making the baseline 3 correct.

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 gives a precise verb+resource+effect: an accord line is replaced by the materials it holds, at the same dose, in place. This clearly separates it from siblings such as insert_accord, view_accord and resync_accord without needing to open 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?

It states the explicit trigger condition ('when the user wants an accord line replaced by the materials it holds') and points to undo_last_change as the reversal path. It does not state when not to use it (e.g. use view_accord for inspection), so a 5 is not warranted.

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