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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered by structured data. The description adds the return keys {ev_value, lv_value, shutter_speed_s}, but that duplicates the declared output schema and omits any behavioural context such as unit assumptions or how conflicting inputs are resolved.

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 compact sentences, front-loaded with the core calculation and with no filler. The return-value sentence is largely redundant given an output schema exists, which is the only wasted space.

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?

An output schema and full annotations exist, so return format and safety need not be restated. The remaining gap is the unresolved tension between the description's 'given the other two' and the three required parameters, leaving an agent unsure whether one input is optional.

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 schema already defines all three parameters and their units, giving a baseline of 3. However the description states a value is 'missing' and derived from 'the other two', while the schema marks iso, aperture and shutter_speed as all required — this is misleading about whether any parameter is optional, which could cause an agent to omit a required argument.

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 names a specific verb (calculate) and resource (the missing exposure value among aperture, shutter speed, ISO), so an agent can distinguish it from neighbouring photography calculators like calculate_depth_of_field or calculate_crop_factor. It is clear, but the 'missing ... given the other two' framing conflicts with a schema that requires all three, which slightly muddies the purpose.

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?

Usage is only implied by the calculation description plus a pointer to list_bundles for related 'photographie' calculators. There is no explicit when-to-use statement and no guidance on choosing this over the other exposure/photography siblings such as calculate_hyperfocal_distance or calculate_crop_factor.

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