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

Annotations cover only the safety profile (readOnly, non-destructive, openWorld=false), and the description goes well beyond them: LLM-backed execution, anonymized rate limits (6/min, 30/h), deterministic matching, and specific result fields (selected.fixed, fixed_verdict, fixed_fails). This is exactly the extra behavioral context an agent needs and cannot get from 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?

Two sentences, front-loaded with the primary action and the fallback/`fixed` path, with no filler. The parenthetical output-field list is dense but earns its place since no output schema exists.

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?

No output schema exists, yet the description names the returned evidence fields, documents the rate limit, and explains determinism and the role of `fixed`. For a 2-parameter LLM-backed assembly tool, nothing an agent needs to invoke it correctly is missing.

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 baseline is 3, but the description adds real meaning: `fixed` ids stay in their subsystems, are validated against stated requirements, and surface as selected.fixed/fixed_verdict/fixed_fails. The example task for `q` also clarifies its acceptable syntax beyond the schema's generic description.

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 ('Assemble a whole spacecraft bus') and the full pipeline: planning, deterministic matching, budget computation, rationale. It also names the sibling tools (match_components, get_datasheet_digest) whose output feeds it, so an agent can place it in the workflow without opening a 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?

Explains the key usage pattern: pass `fixed` with product ids you have already chosen from match_components or get_datasheet_digest, and the rest is assembled around them. That is clear context for the main branch of use, but there is no explicit statement of when NOT to use it (e.g., when to prefer build_budget or find_data_gaps instead).

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