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

Annotations already declare destructiveHint=true and idempotentHint=true, and the description adds non-obvious behavior: page/section breaks in trmContent replace the row's break flags, trmContent must parse to exactly one block, read-only [[row]]/[[document]] annotations are rejected, and inserts renumber later rows (invalidating stale anchors). This is substantial context beyond the annotations.

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 dense sentences with no filler; the core action and identification keys are front-loaded, and the caveats (renumbering, break flags, rename routing) each carry distinct operational value.

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, non-open-world mutation with full schema coverage and no output schema, the description covers identification, content constraints, and side effects well. It leaves ambiguous whether itemId and atOrder are alternatives or must be combined, which matters since neither is required.

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 100% so baseline is 3, but the description adds real meaning: itemId format example (FR-003), the atOrder staleness rule tying it to a post-insert read, and the constraint that trmContent parses to exactly one block. It does not clarify the either/or relationship between itemId and atOrder, which is not marked required.

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 ('Replace one block') and immediately specifies the two identification keys (TraceID or [[row N]] anchor). It also names the sibling it is not for renames (traceable_trace_id_rename), so an agent can distinguish it from traceable_block_write/delete/write without opening schemas.

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 clear selection guidance between the two identification methods and routing to traceable_trace_id_rename for renames. It also warns that atOrder must come from a read issued after the last insert. It does not explicitly say when not to use this tool versus traceable_block_write, but context is otherwise strong.

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