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

With no annotations provided, the description carries the full burden and does well by disclosing the return values (gross/net of self-weight, governing mode at L/300, utilization, section properties) and the prefilled web_url. It omits output units and detailed assumptions such as load duration or service class, but the planning-estimate caveat mitigates this somewhat.

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?

Three sentences front-load the core function and outputs, then add the safety caveat and web_url note. Every sentence contributes information, with no filler or repetition.

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 calculator with no output schema and no annotations, the description lists what is returned, defines its scope and limitations, and mentions the prefilled beam URL. It does not state output units or all modeling assumptions, but it is sufficient for an agent to decide whether and how to invoke the tool.

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?

The schema already covers all five parameters at 100%, so the baseline is 3. The description adds useful meaning beyond the schema by specifying 'simply supported', 'center point load', and 'gross and net of self-weight', which clarifies how span, load_type, and beam geometry are interpreted.

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 states a specific calculation: 'Allowable load on a simply supported rectangular timber beam' under Eurocode 5/EN 338 conventions, and enumerates concrete outputs such as allowable UDL, center point load, governing mode, utilization, and section properties. This makes the tool's function clear and distinguishable from sibling volume/weight/coverage calculators.

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 clearly frames when to use the tool ('planning estimate') and gives an explicit exclusion: 'NOT a structural design - verify with an engineer.' It does not name alternative sibling tools, so routing among related calculators like rough_sizing 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.