upsert_symbol

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

The annotations declare destructiveHint=true and readOnlyHint=false, so the description doesn't need to state that it modifies, but it does not add behavioral context beyond that. It doesn't mention that it might overwrite existing symbols, require specific permissions, or affect revision tracking. The description's statement about not touching PLC setup is useful but limited.

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 description is a single, concise sentence that efficiently communicates the core purpose and a key constraint. No wasted words.

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?

Despite having an output schema (which may explain return values), the description lacks critical context: it does not explain the upsert semantics (how it decides to create vs update), the role of expected_revision for concurrency, or conditions under which the operation might fail. Given the tool's mutation nature and many parameters, more guidance is needed.

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?

With 0% schema description coverage, the description should compensate, but it only mentions 'global/local' scope and does not explain the meaning of key parameters like expected_revision, program_name, or address format. It does not clarify how the upsert logic works (e.g., how it identifies an existing symbol). This is a significant gap for an 8-parameter tool.

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 clearly states the action (create or update) and the resource (program symbol), and adds scope distinction (global/local) and explicitly excludes touching PLC setup or I/O tables. This distinguishes it from sibling tools like delete_symbol and list_symbols, though it doesn't explicitly name them.

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 implies usage for creating/updating symbols, and the exclusion of PLC setup/I/O tables provides some direction on what not to use it for. However, it does not explicitly say when to use this versus alternatives like apply_program_patch or set_rung_comment, nor does it provide prerequisites like needing a loaded project.

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