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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower, but the description adds genuine behavior: products are counted at the maximum each label suggests per day, country=GB switches the comparison basis to NHS guidance, hidden amounts are flagged rather than dropped, and fish oil is counted via EPA/DHA. These are non-obvious counting rules an agent could not infer.

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-loads the purpose, then examples, then input format, then return shape — a logical order with no filler sentences. It is dense and somewhat long, with several parentheticals, but every clause carries information.

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?

There is no output schema, so the description carries the burden and does so well: it enumerates the returned buckets (totals, other_totals, items, not_found) and explains the comparison basis. For a 2-parameter, single-required-input tool this is complete enough to invoke correctly.

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 detail beyond the schema: a maximum of 6 items, and that entries may be product names, barcodes, or free-text amounts. That extends the accepted input vocabulary rather than restating the semicolon separator.

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 compound action (add up everything someone takes and check the daily totals against adult upper limits), which cleanly separates it from sibling check_dose (single item), get_nutrient, and get_supplement (lookups). The scope — a multi-item stack total — is unambiguous without opening 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?

Gives two concrete trigger scenarios ("I take Centrum, vitamin D 5000 IU and zinc 50 mg, is that too much?" and "is it OK to take OLLY Sleep with extra melatonin?"), which is real usage guidance. It stops short of explicitly routing the agent away from supplementcheck_check_dose or get_nutrient when only one item is involved.

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