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

Annotations already declare readOnlyHint/idempotentHint/destructiveHint=false, so the safe, deterministic nature is covered by structured data. The added value is thin: the 1 ECTS ≈ 25-30 hours fact duplicates the hours_per_credit schema description, and 'Returns expected workload and balance' duplicates what the output schema already exposes.

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?

Four short sentences, front-loaded with the core computation before usage, inputs, returns and discovery pointers. Efficient, though the inputs/returns sentences partly restate structured data.

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?

Output schema exists, so return values need not be documented in prose, and all three parameters are schema-documented. Only the imprecise 'credits target' input phrasing slightly misleads an agent about what to pass.

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 description coverage is 100%, so baseline is 3. The description's input summary ('course hours, credits target') does not match the actual schema fields (hours_per_week, weeks, optional hours_per_credit) and adds no syntax or range detail beyond the schema.

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?

Clear specific verb+resource: 'Estimate ECTS credit workload' with the domain stated ('university course planning across Europe'). It does not, however, distinguish itself from adjacent education-related siblings such as calculate_study_schedule or calculate_gpa_french beyond pointing to bundle discovery.

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?

'Use for university course planning across Europe' gives an implied usage context, and 'See list_bundles for related education calculators' is a soft discovery pointer. There is no explicit when-not-to-use guidance or a named alternative calculator for overlapping needs.

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