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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds real behavioral value beyond that: it discloses the exact solver, the platform-specific lineup rules (DK 6 under $50k; FD MVP 1.5x, 5 more under $100), and the returned fields, which matters since there is no output schema.

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 dense sentences, front-loaded with the core action and platform rules, with no filler. The platform-rules sentence is long but each clause carries usable constraint 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?

For an 11-parameter solver with no output schema and no required params, the description covers the domain rules, the option set, and the return payload (lineup salary/projection/ceiling/ownership plus fighter exposure). 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 the baseline is 3. The description goes further by tying parameters to domain meaning the schema omits — lock/exclude by name, the objective blend ratio, ownership cap semantics, and the DK/FD lineup structures that govern count and min_unique behavior.

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 (Builds) and resource (UFC lineups) with an exact solver, and names the two supported platforms. It is clearly the MMA member of the optimizer sibling family (invoke_lol_optimizer, invoke_nba_optimizer, etc.) without needing to open 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?

Gives clear usage context: objective=proj is for cash games, ceil for tournaments, and max_total_own is flagged 'For tournaments'. However, it never names an alternative tool (e.g. invoke_mma_projections or invoke_mma_sim_picks) or states when NOT to use it, so it stops short of explicit routing.

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