Modify railings

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

Annotations already declare destructive/idempotent/not-read-only, so the safety profile is partially covered. The description adds real value beyond them: it discloses the one-undo-step batching, the path-immutability constraint, and the return shape [{guid} | {error}], which the agent cannot get from structured fields since there is no output schema.

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?

Two sentences that are front-loaded with the core action and constraint. The property enumeration is dense but earns its place as a quick capability summary; no filler.

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 full annotation coverage and no output schema, the description supplies the crucial extras: undo behavior, the path-immutability limitation, and the return format. Minor gap is the lack of any note on batch failure semantics (partial success vs all-or-nothing per item).

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%, so the schema fully documents all parameters; baseline is 3. The description names a subset of editable fields (height, bottom offset, reference line side, offsets, pens), which reinforces but does not extend the schema.

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 ("Changes existing railings") and enumerates the modifiable properties, so the agent understands it is a mutation, not a creation or query. It does not name sibling tools (create_railings, modify_elements) to differentiate, but the scope is 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?

The clause "The path cannot be changed (move/rotate or recreate)" implicitly routes path edits to other tools, which is useful. However, there is no explicit when-to-use framing, no prerequisites, and no direct naming of alternative tools.

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