Update surface

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

Annotations already declare readOnly=false, idempotent=true, destructive=false, so safety is covered; the description adds genuinely new behavioral context with 'Only the given fields change', i.e. merge/partial-update semantics rather than replacement, which is the key fact an agent needs before calling an update tool. It does not say what happens for an unknown ID or how nested layers/materials are reconciled, so it is not a 5.

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?

The core action and the merge rule are front-loaded in two short sentences with no filler. The appended rules pointer is terse and useful, though the embedded '<id>' quoting is slightly cryptic and costs a little polish.

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 31-parameter tool with nested objects, five enums, and no output schema, the definition is thin: it never addresses the interaction constraints encoded in the schema (hrrpua vs mlrpua exclusivity, reaction_mode material vs manual, layered vs burner surfaces). The SURF-001 knowledge-search pointer partially compensates by routing the agent to external rules, but nothing is stated inline.

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% and each of the 31 properties, including nested layer/material and injection objects, is documented inline. The description contributes no additional per-parameter meaning beyond the merge semantics already counted elsewhere, so the baseline 3 applies.

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+resource with the FDS domain term (&SURF) and the lookup key (by ID), which is enough to separate it from add_surface / remove_surface / assign_surface. It does not explicitly name an alternative tool, so it stops short of the top score, but the action 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?

There is no explicit when/when-not guidance versus siblings such as add_surface, update_material, or assign_surface. The '[bulc-mcp rules] SURF-001 — bulc_knowledge_search' line functions as a prerequisite pointer, implying the caller should consult a rule before editing, but no condition or exclusion is spelled out.

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