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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=true and openWorldHint=false, so the safety and repeatability profile is supplied structurally. The description adds only the field list, saying nothing about whether omitted fields stay unchanged, what happens to an unknown assignmentId, or what a partial update returns.

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?

A single front-loaded sentence with the verb and resource first and the mutable facets after. No filler, no repetition of annotation data, nothing that could be cut without losing content.

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?

With 10 parameters, full schema coverage and annotations covering the safety profile, the definition is serviceable. The real gap is update semantics for a partial-mutation tool: whether unspecified fields are preserved, and how the paired ID/name parameters interact, is left entirely unstated.

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 the baseline is 3. The description restates categories already documented in the schema (date, time, worker, project, status) and adds nothing about precedence between workerId/workerName or projectId/projectName, nor about the note field.

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 (updates) plus resource (existing planbook assignment) and enumerates the mutable facets: date, time, team member, project, status. The word 'existing' distinguishes it from createAssignment, though no sibling is named explicitly.

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?

'Existing' implies this is not the creation path, so the agent can infer it applies to already-created assignments. However, there is no guidance on when to use this versus siblings like updateTaskStatus or updateProjectStatus, and no prerequisites or exclusion conditions are given.

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