sym_info

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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and closed-world, so the safety profile is covered. The description does add one genuinely useful behavioral note beyond that: derived symbols are returned flattened as KiCad places them, which affects how output should be read. It says nothing about error behavior for an unknown lib_id or about output size/pagination, so it adds some but not rich context.

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, front-loaded with the scope ('Everything about one library symbol') followed by the content list, with a single closing caveat about derived symbols. The long enumeration is dense but each item is informative rather than 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?

An output schema exists, so the description need not explain return structure, and annotations cover safety. For a read-only single-entity lookup with two well-documented parameters, the description is sufficient; only the lack of sibling routing keeps it from being fully complete.

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%; lib_id's format and project_path's library-shadowing semantics are fully documented in the schema itself. The description adds no parameter-level information (e.g., that project_path changes which symbol definition wins), so 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?

The description names a specific resource (one library symbol) and enumerates exactly what is retrieved: description, datasheet, default footprint, footprint filters, units, and every pin with number/name/electrical type. That is far more than a restatement of the name. It stops short of naming siblings (lib_search, lib_fetch, fp_info) that an agent might confuse it with.

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?

Usage is only implied: the exhaustive content list signals 'call this when you need full detail on a single known symbol', and the required lib_id implies a symbol already identified. There is no explicit when-to-use statement, no exclusions, and no routing to lib_search (to find a symbol) or fp_info (the footprint counterpart).

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