Architecture: Symbol

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

Annotations only declare destructiveHint=false and a title, but the description adds substantial behavioral context: sizing semantics (paper mm × scale, not standard values) and a full list of refusal conditions that all occur 'before any write'. This atomicity guarantee is exactly the kind of write-safety detail an agent needs and goes well 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?

Front-loaded with the purpose, then a sizing note, then the refusal list. Dense but every clause carries information; the long refusal enumeration is justified because it defines the tool's contract. Slightly sprawling but not wasteful.

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 return values needn't be explained, and the description covers kinds, sizing, and validation thoroughly. The only gap is the lack of explicit alternative-routing against sibling tools, which leaves the agent to infer which symbol tool to pick.

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 the baseline is 3, but the description adds real meaning beyond the schema: it explains that sizes are the server's declared drafting sizes (16 mm north-arrow circle, 10 mm bubbles) rather than standards values, and it ties each refusal condition to specific parameter constraints (unknown side, non-finite level, invalid lang).

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+target: 'Draw one architectural symbol on the arch symbol layer.' This clearly distinguishes it from the many other symbol/geometry tools (pid_symbol_insert, weld_symbol, centre_marks, arch_wall) without needing the schema.

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 description enumerates the four kinds (north_arrow, section_mark, level, elevation_mark) and their refusal conditions, which implies the intended contexts. However, it never routes the agent explicitly: there is no 'use X instead' guidance against close siblings like section_line, weld_symbol, or pid_symbol_insert, so alternative selection is left to inference.

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