Improve instructions on prompt templates, adding link to new docs section

Improve other docstrings in templates and add missing key `fixed_tools`

.serena/project.yml

@@ -68,8 +68,9 @@ excluded_tools: []
 # Find the list of tools here: https://oraios.github.io/serena/01-about/035_tools.html
 included_optional_tools: []
 
-# initial prompt for the project. It will always be given to the LLM upon activating the project
-# (contrary to the memories, which are loaded on demand).
+# initial prompt for the project,  which will be provided to the LLM upon project activation
+# (or within Serena's initial instructions if the project is activated at startup).
+## See:  https://oraios.github.io/serena/02-usage/050_configuration.html#prompt-templates
 initial_prompt: |
   {{ embed_memory("critical_info") }}
 

src/serena/resources/config/contexts/context.template.yml

@@ -1,11 +1,28 @@
-# See Serena's documentation for more details on concept of contexts.
-description: Description of the context, not used in the code.
-prompt: Prompt that will form part of the system prompt/initial instructions for agents started in this context.
+# See Serena's documentation for more details on concept of contexts:
+# https://oraios.github.io/serena/02-usage/050_configuration.html#contexts
+description: Description of the context (meta-information only)
+
+# define a prompt which will be included in the system prompt when agents are started in this context.
+# See:  https://oraios.github.io/serena/02-usage/050_configuration.html#prompt-templates
+prompt: |
+  This prompt will form part of the system prompt/initial instructions for agents started in this context.
+  Add as much content as needed.
+  Leave it undefined if no prompt is needed, i.e.
+     prompt: null
+
+# tools to be excluded in this context.
+# Find the list of tools here: https://oraios.github.io/serena/01-about/035_tools.html
 excluded_tools: []
 
-# several tools are excluded by default and have to be explicitly included by the user
+# included tools that would otherwise be excluded (particularly optional tools that are disabled by default).
+# Find the list of tools here: https://oraios.github.io/serena/01-about/035_tools.html
 included_optional_tools: []
 
+# fixed set of tools to use as the base tool set (if non-empty), replacing Serena's default set of tools.
+# This cannot be combined with non-empty excluded_tools or included_optional_tools.
+# Find the list of tools here: https://oraios.github.io/serena/01-about/035_tools.html
+fixed_tools: []
+
 # mapping of tool names to an override of their descriptions (the default description is the docstring of the Tool's apply method).
 # Sometimes, tool descriptions are too long (e.g., for ChatGPT), or users may want to override them for another reason.
 tool_description_overrides: {}

src/serena/resources/config/modes/mode.template.yml

@@ -1,8 +1,25 @@
-# See Serena's documentation for more details on concept of modes.
+# See Serena's documentation for more details on concept of modes:
+# https://oraios.github.io/serena/02-usage/050_configuration.html#modes
 description: Description of the mode (meta-information only)
+
+# define a prompt which will be included in the system prompt when this mode is activated
+# (or will be provided in the project activation message if the mode is activated dynamically).
+# See:  https://oraios.github.io/serena/02-usage/050_configuration.html#prompt-templates
 prompt: |
-  Provide a prompt that will form part of the instructions sent to the model when this mode is activated.
-# tools that are to be excluded by this mode
+  This prompt will form part of the system prompt/initial instructions for agents started in this context.
+  Add as much content as needed.
+  Leave it undefined if no prompt is needed, i.e.
+     prompt: null
+
+# tools to be excluded in this context.
+# Find the list of tools here: https://oraios.github.io/serena/01-about/035_tools.html
 excluded_tools: []
-# several tools are excluded by default and have to be explicitly included by the user
-included_optional_tools: []
+
+# included tools that would otherwise be excluded (particularly optional tools that are disabled by default).
+# Find the list of tools here: https://oraios.github.io/serena/01-about/035_tools.html
+included_optional_tools: []
+
+# fixed set of tools to use as the base tool set (if non-empty), replacing Serena's default set of tools.
+# This cannot be combined with non-empty excluded_tools or included_optional_tools.
+# Find the list of tools here: https://oraios.github.io/serena/01-about/035_tools.html
+fixed_tools: []