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

With readOnlyHint=true already declared, the description still adds substantial behavioral context: null-field semantics, the distinction between role as a speaker-level note and a session role, ordering by first stage appearance, and the program-derived roster behavior with source and kind values. This goes well beyond the annotation baseline and contains no contradiction.

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?

The description is dense but every sentence earns its place: field list, ordering, filtering, null behavior, and fallback construction. No filler or repetition of schema details, and the most important scoping information is front-loaded.

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?

There is no output schema, so the description carries the full burden of describing return values, ordering, null handling, and edge cases. It covers all of these clearly, and the only remaining ambiguity—how this relates to events_speaker_detail—is a sibling differentiation matter rather than a completeness gap for calling the tool.

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 schema already documents both parameters fully, including the day filter timezone semantics and the flexible eventIdOrSlug forms. The description only echoes 'Optionally filter to one day' without adding new parameter-level meaning, so the baseline 3 applies.

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 states a specific verb and resource: listing the people on an event's programme, with a detailed breakdown of returned fields. It is clear and unambiguous, but it never explicitly distinguishes itself from the sibling events_speaker_detail, so an agent must infer the boundary between 'all speakers for an event' and 'one speaker's detail'.

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?

The description provides clear situational context: it is for retrieving an event's speakers, supports optional day filtering, and explains the fallback when no speaker records exist. It does not, however, state when to prefer this tool over alternatives like events_speaker_detail or events_whats_on, so exclusions are absent.

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